United States Department of Agriculture Natural Resources Conservation Service Agriculture Handbook Number 590

Ponds — Planning, Design, Construction

Agriculture Handbook 590

Ponds—Planning, Design, Construction

Preface

This handbook describes the requirements for building a pond. It is useful to the landowner for general information and serves as a reference for the engineer, technician, and contractor. In fulfilling their obligation to protect the lives and property of citizens, most states and many other government entities have laws, rules, and regulations governing the installation of ponds. Those responsible for planning and designing ponds must comply with all such laws and regulations. The owner is responsible for obtaining permits, performing necessary maintenance, and having the required safety inspections made.

which served as a sediment basin while homes in the background were being constructed. Design. Such a pond. and as resting places during migration
7
Figure 9
The shoreline of a well-designed pond is protected from erosion by the addition of stone. irrigation. now adds variety and value to the community
8
Figure 11
A guide for estimating the approximate size of a drainage area (in acres) required for each acre-foot of storage in an embankment or excavated pond
10
Figure 12
Recommended minimum depth of water for ponds in the United States
11
Figure 13
Land with permanent vegetation makes the most desirable drainage area
12
Figure 14
A preliminary study of two alternative sites for a pond to be used for livestock water.Agriculture Handbook 590
Ponds—Planning. reflecting nearby trees. Construction
Figures
Figure 1 Figure 2
Typical embankment and reservoir This pond supplies water to a stockwater trough used by cattle in nearby grazing area
1 2
Figure 3 Figure 4
Water is pumped out of this pond for irrigation A pond stocked with fish can provide recreation as well as profit
3 4
Figure 5
A dry hydrant is needed when a pond is close enough to a home or barn to furnish water for fire fighting
5
Figure 6 Figure 7
Details of a dry hydrant installation Ponds are often used for private as well as public recreation
5 6
Figure 8
Waterfowl use ponds as breeding. watering places. and recreation
12
Figure 15
Approximate geographic boundaries for NRCS rainfall distributions
19
vi
. increases the value of the surrounding land
7
Figure 10
This pond. feeding.

Design. political beliefs. (Not all prohibited bases apply to all programs. Washington. and marital or familial status. sex. or call 1-800-245-6340 or (202) 720-1127 (TDD). age. 20250. USDA is an equal opportunity employer. Department of Agriculture. etc.
x
. disability. DC.) Persons with disabilities who require alternate means for communication of program information (Braille.Agriculture Handbook 590
Ponds—Planning. religion. Construction
Issued June 1982 Revised November 1997
The United States Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race. audiotape. U.) should contact the USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint. color. large print. national origin. write the Secretary of Agriculture.S.

The land slope may range from gentle to steep. conservationists. field and orchard spraying. inlet crest
Top of settled fill
Normal pool
Auxiliary spillway Inlet section Barrel Backslope
Frontslope
O se utle ct t io n
Core trench
Outlet channel 1
. The information comes from the field experience and observation of land users. recreation. Because the water capacity is obtained almost entirely by digging. and ponds are one of the most reliable and economical sources of water. commercial or industrial buildings.
Figure 1
Cross section (not to scale) Temporary pool
An embankment pond (fig. or in interrupted use of public utilities.
Typical embankment and reservoir
Top of constructed fill Stage P. main highways. wildlife habitat. Local information is essential. The demand for water has increased tremendously in recent years. Design. or railroads. Some ponds are built in gently to moderately sloping areas and the capacity is obtained both by excavating and by building a dam. and landscape improvement. More will be needed in the future. fire protection. energy conservation. Construction
Ponds—Planning. By 1980 more than 2. Design. and other specialists. Ponds are now serving a variety of purposes. The criteria and recommendations are for dams that are less than 35 feet high and located where failure of the structure will not result in loss of life. erosion control. engineers.S.1 million ponds had been built in the United States by land users on privately owned land. including water for livestock and for irrigation. An excavated pond is made by digging a pit or dugout in a nearly level area. excavated ponds are used where only a small supply of water is needed. and land users are encouraged to consult with specialists experienced in planning and building ponds. 1) is made by building an embankment or dam across a stream or watercourse where the stream valley is depressed enough to permit storing 5 feet or more of water.Agriculture Handbook 590 Agriculture Handbook 590
Ponds — Planning. This handbook describes embankment and excavated ponds and outlines the requirements for building each. Construction
Introduction
For many years farmers and ranchers have been building ponds for livestock water and for irrigation. fish production. in damage to homes.

Design. This can contribute to serious livestock losses and instability in the livestock industry. Areas of abundant forage may be underused if water is not accessible to livestock grazing on any part of that area (fig. Watering places must also be properly distributed in relation to the available forage. and period over which they are served. retards erosion. Kind of livestock Beef cattle and horses Dairy cows (drinking only) Dairy cows (drinking and barn needs) Hogs Sheep Gallons per head per day 12 to 15 15 35 4 2
The amount of water consumed at one pond depends on the average daily consumption per animal.
Figure 2
This pond supplies water to a stockwater trough used by cattle in nearby grazing area
2
. grazing will be concentrated near the water and other areas will be undergrazed.Agriculture Handbook 590
Ponds—Planning. Construction
Water needs
Livestock
Clean water and ample forage are equally essential for livestock to be finished out in a marketable condition. The average daily consumption of water by different kinds of livestock shown here is a guide for estimating water needs.
An understanding of stockwater requirements helps in planning a pond large enough to meet the needs of the stock using the surrounding grazing area. steep areas unfit for cultivation. facilitates pasture improvement practices. Providing enough watering places in pastures encourages more uniform grazing. number of livestock served. and enables farmers to make profitable use of soil-conserving crops and erodible. If stockwater provisions in pasture and range areas are inadequate. 2).

effective
rainfall expected during the growing season. Now many farmers in the East are irrigating their crops. usually less than 50 acres. A properly built and managed pond can yield from l00 to 300 pounds of fish annually for each acre of water surface. The required storage capacity of a pond used for irrigation depends on these interrelated factors: water requirements of the crops to be irrigated. A minimum depth of 8 feet over an area of approximately 1. Ponds of less than 2 acres are popular because they are less difficult to manage than larger ones. Design. The area irrigated from a farm pond is limited by the amount of water available throughout the growing season. a 3-inch application of water on l acre requires 81. which does not have the organized irrigation enterprises of the West.
Figure 3
Water is pumped out of this pond for irrigation
3
. A good fish pond can also provide recreation (fig. Water requirements for irrigation are greater than those for any other purpose discussed in this handbook.
Fish production
Many land users are finding that fish production is profitable. Consequently. losses due to evaporation and seepage. 3). 4) and can be an added source of income should you wish to open it to people in the community for a fee.462 gallons. particularly in the East. Construction
Irrigation
Farm ponds are now an important source of irrigation water (fig. For example. Pond capacity must be adequate to meet crop requirements and to overcome unavoidable water losses.Agriculture Handbook 590
Ponds—Planning. Before World War II irrigation was not considered necessary in the humid East. irrigation from farm ponds generally is limited to high-value crops on small acreages. Your local NRCS conservationist can help you estimate the required capacity of your irrigation pond. application efficiency of the irrigation method. and the expected inflow to the pond.000 square feet is needed for best management. Ponds that have a surface area of a quarter acre to several acres can be managed for good fish production.

the withdrawal rate for fire fighting is high. and engine horsepower. Orchards. Use good quality rubber-lined firehoses. One acre-foot of storage is enough for four streams. a small pump is needed to fill the tank.
Although water-storage requirements for fire protection are not large. however. the amount of water needed for spraying is small. the hose should be no more than 600 feet long. A centrifugal pump operating at 63 pounds per square inch provides a stream of 265 gallons per minute with a nozzle pressure of 50 pounds per square inch. Preferably. capacity. 5 and 6). may require 1. provide enough storage to operate several such streams. If you live in an area protected by a rural fire fighting organization. engines. A typical firehose line consists of 500 feet of 3-inch hose and a 1-1/8 inch smooth nozzle. Also provide for one or more dry hydrants (figs. About l00 gallons per acre for each application is enough for most field crops.Agriculture Handbook 590
Ponds—Planning.
Fire protection
A dependable water supply is needed for fighting fire.000 gallons or more per acre for each spraying.
Figure 4
A pond stocked with fish can provide recreation as well as profit
4
. and similar equipment can furnish the information you need about pump size. or other buildings. barn. Construction
Field and orchard spraying
You may wish to provide water for applying pesticides to your field and orchard crops. Generally. Design. Your local dealer in pumps. Provide a means of conveying water from the pond to the spray tank. 2-1/2 to 3 inches in diameter. A satisfactory fire stream should be at least 250 gallons per minute with pressure at the nozzle of at least 50 pounds per square inch. place a pipe through the dam and a flexible hose at the downstream end to fill the spray tank by gravity. If your pond is located close to your house. In an excavated pond. but it must be available when needed. Such a stream running for 5 hours requires 1/4 acre-foot of water. provide a centrifugal pump with a power unit and a hose long enough to reach all sides of all the buildings. In an embankment pond. Fire nozzles generally are l inch to 1-1/2 inches in diameter.

Waterfowl and other wildlife
Ponds attract many kinds of wildlife. 9). The state board of health or a similar agency administers such laws and regulations. water must be tested and approved before public use is permitted. boat ramps or docks. and sanitary facilities. Many land users realize additional income by providing water for public recreation. particularly where the food supply is ample (fig. Generally. 7). picnic tables. Construction
Recreation
A pond can provide many pleasant hours of swimming. fireplaces. the area must be large enough to accommodate several parties engaged in whatever recreation activities are provided. Minimum facilities for public use and safety are also needed. Ducks often use northern ponds as breeding places. These facilities include access roads. patio. boating. To protect public health. most states have laws and regulations that require water supplies to meet certain prescribed standards if they are to be used for swimming and human consumption. drinking water. A pond visible from a home. Contact your local health agency to become familiar with those regulations before making extensive plans to provide water for public recreation. If a pond is to be used for public recreation. Upland game birds use ponds as watering places. suburban. Ponds in rural. 8).
Landscape quality
Water adds variety to a landscape and further enhances its quality. A pond used for swimming must be free of pollution and have an adequate depth of water near a gently sloping shore.
Figure 7
Ponds are often used for private as well as public recreation
6
. or entrance road increases the attractiveness of the landscape and often increases land value. and fishing. The surrounding area can be made into an attractive place for picnics and games (fig. and urban areas help to conserve or improve landscape quality. parking areas. Design. supply enough water to overcome evaporation and seepage losses and to maintain a desirable water level. If the public is invited to use a pond for a fee. Reflections in water attract the eye and help to create a contrast or focal point in the landscape (fig.
There are also rules and regulations for building and maintaining public sanitary facilities.Agriculture Handbook 590
Ponds—Planning. Migratory waterfowl often use ponds as resting places in their flights to and from the North.

and as resting places during migration
Figure 9
The shoreline of a well-designed pond is protected from erosion by the addition of stone. Construction
Figure 8
Waterfowl use ponds as breeding. Design. Such a pond. reflecting nearby trees. increases the value of the surrounding land
7
.Agriculture Handbook 590
Ponds—Planning. feeding. watering places.

10).
Figure 10
This pond. now adds variety and value to the community
8
. Good design includes consideration of size. a pond’s appearance can be improved by using appropriate principles and techniques of design. and adding landscape measures (fig. fish production. Consult a landscape architect for additional information and special designs. Second.
Multiple purposes
You may wish to use the water in your pond for more than one purpose. If so. the standards for dam design should be used. Some combinations. two additional factors must be considered. which served as a sediment basin while homes in the background were being constructed. relationship to the surrounding landscape and use patterns. such as irrigation and recreation. If a sediment basin is to be cleaned and reconstructed as a water element. site visibility. making boating and swimming impractical. to provide water for livestock. You would probably use most of the water during the irrigation season. treating the shoreline. generally are not compatible. and shoreline configuration. for example.Agriculture Handbook 590
Ponds—Planning. Design.
First. Your local NRCS conservationist can help you apply the basic principles and design techniques. in estimating your water requirements you must total the amounts needed for each purpose and be sure that you provide a supply adequate for all the intended uses. make sure that the purposes for which the water is to be used are compatible. Construction
Regardless of its purpose. and spraying field crops. Ponds used temporarily for grade control or as sediment basins associated with construction sites can be converted later into permanent ponds by cleaning out the sediment.

However. you must notify the utility company before starting construction and obtain permission to excavate. or highways. locate the pond as close to the major water use as practicable. The physical characteristics that directly affect the yield of water are relief. the intended use of the water may not be practical. Well-spaced watering places encourage uniform grazing and facilitate grassland management. railroads. A good site generally is one where a dam can be built across a narrow section of a valley. If a site crossed by pipelines or cable must be used. mine dumps. Analysis and selection of pond sites should be based on landscape structure and associated ecological functions and values. Be sure that no buried pipelines or cables cross a proposed pond site. and similar areas does not reach the pond. injury to persons or livestock. feedlots. Design. and practical site. industrial buildings.
Area adequacy of the drainage
For ponds where surface runoff is the main source of water. The amount of runoff that can be expected annually from a given watershed depends on so many interrelated factors that no set rule can be given for its determination. They could be broken or punctured by the excavating equipment. the drainage area should not be so large that expensive overflow structures are needed to bypass excess runoff during large storms. Space watering places so that livestock does not travel more than a quarter mile to reach a pond in rough. hire a qualified person to investigate other potential sites to reduce the possibility of failure from improper design or construction. damage to homes. Storm characteris9
. esthetic. consider more than one location and study each one to select the most ecologically appropriate. such as for irrigation or fire protection. nearly level areas. especially if the general public is charged a fee to use
the pond. locate the pond where the largest storage volume can be obtained with the least amount of earthfill. make a pond available in or near each pasture or grazing unit. or interrupted use of public utilities. and surface storage. plant cover. but also in injury to the operator of the equipment. or other forms of recreation must be reached easily by automobile. Avoid sites under powerlines. corrals. Refer to figure 1 and the glossary to become familiar with the components of a pond and associated dam. and the slope of the valley floor permits a large area to be flooded. The wires may be within reach of a fishing rod held by someone fishing from the top of the dam. Avoid pollution of pond water by selecting a location where drainage from farmsteads. If pond water must be conveyed for use elsewhere. Ponds for fishing. Use permanent or temporary measures. If the only suitable pond site presents one or more of these hazards. to redirect runoff from these sources to an appropriate outlet until the areas can be treated.Agriculture Handbook 590
Ponds—Planning. If possible. Relationship of the site to other ecological features within the landscape is critical to achieving planned objectives. swimming. If farm ponds are used for watering livestock. which can result not only in damage to the utility. the side slopes are steep. Conveying water is expensive and. if distance is excessive. Avoid large areas of shallow water because of excessive evaporation and the growth of noxious aquatic plants. broken country or more than a mile in smooth. boating. For economy. The success of an income-producing recreation enterprise often depends on accessibility. soil infiltration. Weighing both onsite and offsite effects of constructing a pond is essential in site selection. sewage lines. Do not overlook the possibility of failure of the dam and the resulting damage from sudden release of water. the contributing drainage area must be large enough to maintain water in the pond during droughts. Forcing livestock to travel long distances to water is detrimental to both the livestock and the grazing area. and preliminary studies are needed before final design and construction. Such sites also minimize the area of shallow water. Construction
Preliminary investigations
General considerations
Selecting a suitable site for your pond is important. such as diversions. Do not locate your pond where failure of the dam could cause loss of life.

0
200
400
12087
600 Mi
10
. such as moderate slopes. and duration of rainfall. intensity. Figure 11 is a general guide for estimating the approximate size of drainage area needed for a desired waterstorage capacity.
Figure 11
A guide for estimating the approximate size of a drainage area (in acres) required for each acre-foot of storage in an embankment or excavated pond
12 8 50 6030
8
8 30
60
50
3 35 20 12 8 5 3
26083
5 3 1.
Minimum pond depth
To ensure a permanent water supply. Each must be considered when evaluating the watershed area conditions for a particular pond site.5
2
3 2 3 1. the water must be deep enough to meet the intended use requirements and to offset probable seepage and evaporation losses. some adjustments may be necessary to meet local conditions. normal soil infiltration. If reliable local runoff information is available. Figure 12 shows the recommended minimum depth of water for ponds if seepage and evaporation losses are normal.
To apply the information given in figure 11. Design. also affect water yield. These characteristics vary widely throughout the United States. fair to good plant cover.5
12033 FL
100
100 60 60
35 100 120 100 60 60 50 8 35 20 12 20 35 12 8 12 5 20 35 3 2 3
2
2 2 1.5 2
Note: The numbers in Mountainous areas (green) may not apply because rainfall in them is spotty and varies sharply. Reduce the values by as much as 25 percent for drainage areas having extreme runoff-producing characteristics.Agriculture Handbook 590
Ponds—Planning. and normal surface storage. a pond located in westcentral Kansas with a capacity of 5 acre-feet requires a drainage area of at least 175 acres under normal conditions. Deeper ponds are needed where a permanent or year-round water supply is essential or where seepage losses exceed 3 inches per month. Average physical conditions in the area are assumed to be the normal runoff-producing characteristics for a drainage area.5 3 5 2 5
CT 25001
120
30
3 5
3 3
3
80
60 80
8
60 1 2
12
120
80
3 3
12
1 2 8
100
12 0
35
80 60 80
5
3
35
0
30
DE
3 5 5
2
140
50
100
80
35
30 60
60
60
50
35 60
1
00
35
60
35
1
3
20
12 8
3
35 60 30 140 100 140
5
3
5
1
1. Modify the values in the figure for drainage areas having characteristics other than normal. use it in preference to the guide.5 2 2 2 1. These vary in different sections of the country and from year to year in any one section. Construction
tics. such as amount. For example. Increase them by 50 percent or more for low runoffproducing characteristics.

Agriculture Handbook 590
Ponds—Planning. stripcropping. 13). are the next best watershed conditions. the inflow must be reasonably free of silt from an eroding watershed. In any event. Construction
Drainage area protection
To maintain the required depth and capacity of a pond. If an eroding or inadequately protected watershed must be used to supply pond water. Design. or forbs is the most desirable drainage area (fig. Cultivated areas protected by conservation practices. protection of the drainage area should be started as soon as you decide to build a pond. or conservation cropping systems.
Figure 13
Land with permanent vegetation makes the most desirable drainage area
Figure 12
Recommended minimum depth of water for ponds in the United States
Legend
Wet Humid Moist subhumid Dry Subhumid Semiarid Arid 5 foot pond depth 6–7 foot pond depth 7–8 foot pond depth 8–10 foot pond depth 10–12 foot pond depth 12–14 foot pond depth
0 200 400 600 Mi
11
. The best protection is adequate application and maintenance of erosion control practices on the contributing drainage area. Land under permanent cover of trees. such as terraces. conservation tillage. grass. delay pond construction until conservation practices are established.

5 feet at the dam has an approximate capacity of 16 acre-feet (0. 14). Vegetation adds aesthetic value by casting reflections on the water. A simple method follows: • Establish the normal pond-full water elevation and stake the waterline at this elevation. Identify major viewpoints (points from which the site is viewed) and draw the important sight lines with cross sections.
Landscape evaluation
Alternative pond sites should be evaluated for potential visibility and compatibility with surrounding landscape characteristics and use patterns (fig. and recreation
*
Vegetable garden * Viewpoints Sight lines House
*
Barn
x x x x x x x x
Pond A
x x x x
Stockwater trough
Pond B
12
.4 times the maximum water depth in feet measured at the dam.2 acres and a depth of 12.5 = 16 acre-feet) [1 acre-foot = 325. Design.4 x 3. In addition to the more typical farm and residential sites. and other low production areas. where needed. If feasible. • Multiply the surface area by 0. minor changes in the dam alignment and spillway location can shift these elements out of view and reduce their prominence. abandoned rural mines. provides shade on summer days. wildlife habitat. or spillway. a pond with a surface area of 3. locate the pond so that the major sight line crosses the longest dimension of water surface. Often. ponds can be located on poor quality landscapes to rehabilitate abandoned road borrow areas. • Measure the width of the valley at this elevation at regular intervals and use these measurements to compute the pond-full surface area in acres. dumping sites. Construction
Pond capacity
Estimate pond capacity to be sure that enough water is stored in the pond to satisfy the intended use requirements. to determine visibility.651 gallons]. pipe inlet. The pond should be placed so that a viewer will see the water first before noticing the dam. or visual interest.2 x 12.Agriculture Handbook 590
Ponds—Planning. irrigation. locate your pond so that some existing trees and shrubs remain along part of the shoreline.
Figure 14
A preliminary study of two alternative sites for a pond to be used for livestock water. and helps blend the pond into the surrounding landscape. A pond can often be located and designed so that an island is created for recreation. If possible. For example.

They are chiefly deep. The runoff potential is high. soil groups. The runoff potential is low. affect the rate at which water runs off.
13
. Because these numbers relate to a set of curves developed from the NRCS runoff equation. Terraces and diversions. assume that the watershed above a pond is mainly (three-fourths) in good pasture and a soil in hydrologic group B. is the potential source of water that may run off small watersheds. They are chiefly moderately deep. soils with a permanent high water table. B—These soils have a moderate infiltration rate when thoroughly wet. A weighted curve number for the total watershed would be: 3/4 x 61 = 46 (approximately) 1/4 x 76 = 20 (approximately) Weighted = 66
Hydrologic groupings of soils
Soils are classified in four hydrologic groups according to infiltration and transmission rates: A—These soils have a high infiltration rate. soils with a claypan at or near the surface. The kind of soil and the type of vegetation affect the amount of water that runs off. well-drained sand or gravel. The NRCS district conservationist or your county extension agent can help you classify the soils for a given pond site in one of the four hydrologic groups. Construction
Runoff curve numbers
Estimating storm runoff
The amount of precipitation. The remainder is cultivated with conservation treatment on a soil in hydrologic group C. They are chiefly clay soils that have a high swelling potential.Agriculture Handbook 590
Ponds—Planning. cover conditions. and shallow soils over nearly impervious material. These moderately fine to fine texture soils have a layer that impedes downward movement of water. well-drained soils of moderately fine to moderately coarse texture. D—These soils have a very slow infiltration rate. along with steepness and shape of a watershed. land use.
Tables 1 through 4 show numerical runoff ratings for a range of soil-use-cover complexes. Design. C—These soils have a slow infiltration rate when wet. For example. The watershed upstream from a farm pond often contains areas represented by different curve numbers. they are referred to as curve numbers (CN) in these tables. and watershed slopes. whether it occurs as rain or snow. A weighted curve number can be obtained based on the percentage of area for each curve number. They provide a quick and reliable estimate of runoff rates and associated volumes for a range of storm rainfall amounts. A spillway is provided to bypass surface runoff after the pond is filled. The tables and charts in the following sections should be used to estimate the peak discharge rates for the spillway.

These maps have also been reprinted in Hydrology for Small Urban Watershed. Designing for a 50-year storm frequency is recommended for spillways for
larger dams. Contact your local NRCS field office for rainfall amounts on maps. This means a storm with only a 4 percent chance of occurring in any year or the size beyond which larger storms would not occur more often than an average of once in 25 years. type I and IA represent the Pacific maritime climate with wet winters and dry summers. In figure 15. Rainfall Frequency Atlas of the United States.
Figure 15
Approximate geographic boundaries for NRCS rainfall distributions
Legend
Type I Type IA Type II Type III
0
200
400
600 Mi
19
. Construction
Rainfall amounts and expected frequency
Maps in U.Agriculture Handbook 590
Ponds—Planning. a set of synthetic rainfall distributions having nested rainfall intensities were developed. Type II represents the rest of the country. Technical Release 55. Weather Bureau Technical Paper 40 (USWP-TP-40). Design.S.
Rainfall distribution
The highest peak discharges from small watersheds are usually caused by intense. A 10-year storm frequency may be adequate for sizing the spillway in small ponds. brief rainfalls that may occur as part of a longer duration storm. Different rainfall distributions with respect to time have been developed for four geographic areas of the United States. The spillway for an ordinary farm pond generally is designed to pass the runoff from a 25-year frequency storm. Designing an ordinary pond spillway to accommodate the peak rate of runoff from the most intense rainstorm ever known or anticipated is not practical. For each of these areas. These distributions maximize the rainfall intensities by incorporating selected storm duration intensities within those needed for longer durations at the same probability level. show the amount of rainfall expected in a 24hour period. Type III represents Gulf of Mexico and Atlantic coastal areas where tropical storms bring large rainfall amounts.

Tc can be estimated for small rural watersheds using equation 1. feet 10. Design.5 Time of concentration (Tc). Figure 16 is a nomograph for solving this equation.1 .000
5
pe
T=
2
sh ed
W at
er
0.  1000 − 9   l  CN     Tc = 0. and rainfall distribution are used to estimate the peak discharge rate.Agriculture Handbook 590
Ponds—Planning.
1
4
9 9 5 80 0
. Construction
Peak discharge rate
The slope of the land above the pond affects the peak discharge rate significantly. the larger the peak discharge.7
[Eq.8
(
)
0. %
Figure 16
Time of concentration (Tc) nomograph
100
1. Tc influences the peak discharge and is a measure of how fast the water runs off the land. For the same size watershed. hr flow length. The time of concentration along with the runoff curve number. storm rainfall. 1]
Time of concentration
Time of concentration (Tc) is the time it takes for runoff to travel from the hydraulically most distant point of the watershed to the outlet. the where: Tc = l = CN = Y = time of concentration.
shorter the Tc. ft runoff curve number average watershed slope.5 1140 Y
0.3 . hrs
64
32
16 8
slo
1. This rate is used to design the auxiliary spillway width and depth of flow.0
2
20
7 6 0 50 0 40
3 4 5 6 8 10
0. This means that the peak discharge has an inverse relationship with Tc.000
Flow length (l).

you may need a complete topographic survey of the entire pond site. spillways. Pond surveys generally consist of a profile of the centerline of the dam. This line of levels establishes the height of the dam and the location and elevation of the earth spillway and the principal spillway. the soils remain highly permeable. Some limestone areas are especially hazardous as pond sites. sinks. For larger and more complex ponds.
24
. many soils in these areas are granular. They may empty the pond in a short time. an iron rod driven flush with the ground. All surveys made at a pond site should be tied to a reference called a bench mark. Unless you know that the soils are sufficiently impervious and that leakage will not be a problem. a point on the concrete headwall of a culvert. Coarse-textured sands and sand-gravel mixtures are highly pervious and therefore usually unsuitable. This may be a large spike driven into a tree. Design. Run a similar line of profile levels along the centerline of the auxiliary spillway. Because the granules do not break down readily in water. you should make soil borings at intervals over the area to be covered with water. Construction
Site surveys
Once you determine the probable location of the pond. conduct a site survey to plan and design the dam. Those unfamiliar with the use of surveying instruments should employ a licensed surveyor or other qualified professional. particularly those used for water supply or irrigation. and other features. This line serves as a basis for determining the slope and dimensions of the spillway. Start from a point on the upstream end that is well below the selected normal water surface elevation and continue to a point on the downstream end where water can be safely discharged without damage to the dam. More may be required if there are significant differences. sandy and gravelly clays are usually satisfactory. All the factors that may make a limestone site undesirable are not easily recognized without extensive investigations and laboratory tests.
Embankment ponds
Detailed soils investigation
Soils in the ponded area—Suitability of a pond site depends on the ability of the soils in the reservoir area to hold water. Run a line of profile level surveys along the centerline of the proposed dam and up both sides of the valley well above the expected elevation of the top of the dam and well beyond the probable location of the auxiliary spillway. or channels that are not visible from the surface may be in the limestone below the soil mantle. Foundation conditions—The foundation under a dam must ensure stable support for the structure and provide the necessary resistance to the passage of water. The absence of a layer of impervious material over part of the ponded area does not necessarily mean that you must abandon the proposed site. A simple method of estimating pond capacity is described on page 12. The profile should show the surface elevation at all significant changes in slope and at intervals of no more than 100 feet. It is also used to compute the volume of earthfill needed to build the dam. Three or four borings per acre may be enough if the soils are uniform. a Plasticity Index of more than 10 percent. 200 sieve. Any of these methods can be expensive. The soil should contain a layer of material that is impervious and thick enough to prevent excessive seepage. In addition.Agriculture Handbook 590
Ponds—Planning. and an undisturbed thickness of at least 3 feet do not have excessive seepage when the water depth is less than 10 feet. soils with at least 20 percent passing the No. and enough measurements to estimate pond capacity. a profile of the centerline of the earth spillway. Clays and silty clays are excellent for this purpose. Crevices. or any object that will remain undisturbed during and after construction of the dam. The best clue to the suitability of a site in one of these areas is the degree of success others have had with farm ponds in the immediate vicinity. You can treat these parts of the area by one of several methods described later in this handbook. Generally.

. and clayey silts that have slight plasticity. Some examples are gravelsand-clay mixtures.. Study the natural banks (abutments) at the ends of the dam as well as the supporting materials under the dam. Dispersive soils can be identified by how easily they go into suspension in water. but are highly pervious and do not hold water. place a core of clay material in the center of the fill and flatten the side slopes to keep the line of seepage from emerging on the downstream slope. to prevent excessive or harmful percolation of water through the dam.. The depth of the holes should be at least 1-1/2 times the height of the proposed dam. . Soils containing a high percentage of gravel or coarse sand are pervious and can allow rapid seepage through the dam. Flattening the side slopes of some dams may be necessary to reduce the unit load on the foundation. the surrounding landscape will be left undisturbed and borrow areas will not be visible after the pond has been filled (fig. sand. are relatively impervious. Less desirable but still acceptable foundation materials for ordinary pond dams are gravelly clays.. the rock must be examined for thickness and for fissures and seams through which water might pass. Construction
Soil borings help to investigate thoroughly the foundation conditions under the proposed dam site. Though satisfactory earthfills can be built from soils that vary from the ideal. When using these soils. and by the indefinite
. those that provide both stability and imperviousness. but have a low degree of stability. Ensure there are not any steep dropoffs in the rock surface of the foundation under the dam. clay particles. If the dam is to be placed on rock. and gravel-sand mixtures. silty clays. This material should contain about 20 percent. You can install a cutoff core trench of impervious material under the dam or blanket the upstream face of the dam and the pond area with a leak-resistant material. The best material for an earthfill contains particles ranging from small gravel or coarse sand to fine sand and clay in the desired proportions. the more precautions needed. Enough suitable material should be located close to the site so that placement costs are not excessive. and sand-silt mixtures. are a mixture of coarseand fine-textured soils.
Materials selected must have enough strength for the dam to remain stable and be tight enough. muck. Good foundation materials. and any soil that has a high organic-matter content from the foundation. by the presence of a gelatinous cloud around a clod of soil in distilled water..Agriculture Handbook 590
Ponds—Planning. such as silts and clays. Fill material that has a high clay content swells when wet and shrinks when dry. Design. They are not good foundation materials. 18). Fine-textured materials. but generally are satisfactory for the size of dams discussed in this handbook. sandclay mixtures. gravel-sand-silt mixtures. The exceptions are organic silts and clays. silty and clayey fine sands. when properly compacted. Such materials can be used only if they are sealed to prevent seepage under the dam.. Remove peat. The shrinkage may open dangerous cracks. they represent a serious hazard to the safety of the embankment and should be avoided. Coarse-textured materials. the greater the variance. provide good support for a dam. Soils described as acceptable for foundation material generally are acceptable for fill material.
Figure 18
Borrow material taken from within the reservoir area creates an irregular pond configuration
25
. Steep dropoffs in the rock surface can result in cracking of the embankment. If these soils are dispersive. Fill material—The availability of suitable material for building a dam is a determining factor in selecting a pond site. sandy clays. If fill material can be taken from the reservoir area. such as gravel. by weight.

19). The shape of a pond should complement its surroundings. only handles a small amount of flow. or cracking. The coarse material (sand) settles to the bottom first. Take a representative sample of the fill material and remove any gravel by passing the material through a 1/4-inch sieve or screen. buckling. flowing shorelines generally are more compatible with the patterns and functions found in most landscapes. formerly called a trickle tube. Existing structures. an engineer should be hired to provide the necessary guidance for sampling. inlets. A disadvantage of this type inlet is the larger amount of stage (head over the inlet crest) needed to make the pipe flow at full capacity. For soils consisting mostly of silt. silt. and direct passage around the pond. or plastic. Design. Openings in the vegetation can be used to avoid costly clearing and grubbing. and structures with minimum disturbance. silt. such as stone walls and trails. the right degree of moisture must be maintained during construction for thorough compaction. and clay in a sample of fill material. A pond’s apparent size is not always the same as its actual size. The pipe shall be capable of withstanding external loading with yielding.
Figure 19
The apparent size of the pond is influenced by surrounding vegetation
26
. guide attention to or from the water. A pond surrounded by trees will appear smaller than a pond the same size without trees or with some shoreline trees (fig. vegetation and landform can provide interesting reflections on the water’s surface. and clay by measuring the thickness of the different layers with a ruler. corrugated metal. and using these soils for fill. Its purpose is to aid in keeping the auxiliary spillway dry during the passage of small storm events. Irregular shapes with smooth. For example. Design limitations exist with all materials. If any of these indicators are found at the proposed site. the more sky reflected on the water surface. a drop inlet spillway requires less stage because the size of the inlet may be enlarged to make the barrel flow full. Fill the bottle to about one-third with the sample material and finish filling with water. frame the water to emphasize it. A small principal spillway pipe. Landscape planning—The pond should be located and designed to blend with the existing landform. such as the loess areas of western Iowa and along the Mississippi River in Arkansas. The principal spillway is designed to reduce the frequency of operation of the auxiliary spillway.Agriculture Handbook 590
Ponds—Planning. first obtain a large bottle with straight sides. Pipe materials may be smooth metal.
Spillway requirements
A pipe spillway often is used as well as an earth auxiliary spillway to control runoff from the watershed. Conversely. Construction
length of time they stay in suspension in still water. Mississippi. To estimate the proportion of sand. vegetation. Commonly the principal spillway may be a hooded or canopy inlet with a straight pipe or may be a drop inlet (vertical section) that has a pipe barrel through the dam. and finer material (clay) settles last.
Peninsulas. or islands can be constructed to create diversity in the water’s edge. water. Hooded or canopy inlets are common. The pipe joints and all appurtenances need to be watertight. testing. and Tennessee. the larger a pond appears. High sodium soils identified in the soil survey for the planned area of the embankment also indicate dispersive soils. Shake the bottle vigorously for several minutes and then allow the soil material to settle for about 24 hours. can be retained to control pedestrian and vehicular traffic and minimize disruption of existing use. Estimate the proportion of sand. Landforms can often form the impoundment with minimum excavation. In the area where land and water meet.

The depth is added to the elevation of the spillway crest to determine the maximum elevation to which water will rise in the reservoir. A natural spillway does not require excavation to provide enough capacity to conduct the pond outflow to a safe point of release (fig. degree of erosion resistance. The proper functioning of a pond depends on a correctly designed and installed spillway system. the permissible velocity must be determined. the investigations should be thorough enough to determine whether the soils can withstand reasonable velocities without serious erosion. it will probably be destroyed during the first severe storm if the capacity of the spillway is inadequate. In this case. Earth spillways have limitations. With the required discharge capacity (Q). and the slope of the natural ground (Z2) known. Construction
The principal spillway normally is sized to control the runoff from a storm ranging from a 1-year to a 10-year frequency event. Avoid loose sands and other highly erodible soils.
Table 7
Minimum spillway design storm
Drainage area (acre)
Effective height of dam 1/ (ft)
Storage
Minimum design storm Frequency Minimum duration (hr)
(acre-ft)
(yr)
20 or less 20 or less More than 20 All others
20 or less More than 20 20 or less
Less than 50 Less than 50 Less than 50
10 25 25 50
24 24 24 24
1/ The effective height of the dam is the difference in elevation between the auxiliary spillway crest and the lowest point in the cross section taken along the centerline of the dam. The requirements discussed later for excavated spillways do not apply to natural spillways. the end slope of the embankment (Z1). Design. The function of an auxiliary spillway is to pass excess storm runoff around the dam so that water in the pond does not rise high enough to damage the dam by overtopping.Agriculture Handbook 590
Ponds—Planning. and slope of the channel. a trickle tube shall be installed. If spillway excavation is required. The spillways must also convey the water safely to the
outlet channel below without damaging the downstream slope of the dam. 20). After the spillway capacity requirements are calculated. Table 9 gives the retardance factors for the expected height of the vegetation. the maximum depth of water above the level portion (Hp) can be obtained from table 10. Auxiliary spillways should have the minimum capacity to discharge the peak flow expected from a storm of the frequency and duration shown in table 7 less any reduction creditable to conduit discharge and detention storage. No matter how well a dam has been built. For pond sites where the drainage area is small (less than 20 acres) and the condition of the vegetated spillway is good. Use them only where the soils and topography allow the peak flow to discharge safely at a point well downstream and at a velocity that does not cause appreciable erosion either within the spillway or beyond its outlet. This depends on the size of the drainage area. Table 8 shows the recommended allowable velocity for various cover. Both natural and excavated auxiliary spillways are used.
27
. but the capacity must be adequate. Soil borings generally are required for auxiliary spillways if a natural site with good plant cover is available. no principal spillway is required except where the pond is spring fed or there are other sources of steady baseflow.

The following example shows how to use table 10: Given: Vegetation: good stand of bermudagrass Height: 6 to 10 inches Slope of natural ground: 1.0 percent Solution: From table 9, determine a retardance of C. From table 10, under natural ground slope 1 percent and retardance C column, find Q = 88 ft3/s at Hp = 1.3 ft, and V = 2.7 ft/s. If the freeboard is 1.0 foot, the top of the dam should be constructed 2.3 feet higher than the spillway crest. The velocity is well below the maximum permissible velocity of 6 feet per second given in table 8. Hp can be determined by interpolation when necessary. For a Q greater than that listed in table 10, the spillway should be excavated according to the information in the next section, Excavated auxiliary spillways. Excavated auxiliary spillways—Excavated spillways consist of the three elements shown in figure 21. The flow enters the spillway through the inlet channel. The maximum depth of flow (Hp) located upstream from the level part is controlled by the inlet channel, level part, and exit channel. Excavation of the inlet channel or the exit channel, or both, can be omitted where the natural slopes meet the minimum slope requirements. The direction of slope of the exit channel must be such that discharge does not flow against any part of the dam. Wing dikes, sometimes called kicker levees or training levees, can be used to direct the outflow to a safe point of release downstream. The spillway should be excavated into the earth for its full depth. If this is not practical, the end of the dam and any earthfill constructed to confine the flow should be protected by vegetation or riprap. The entrance to the inlet channel should be widened so it is at least 50 percent greater than the bottom width of the level part. The inlet channel should be reasonably short and should be planned with smooth, easy curves for alignment. It should have a slope toward the reser-

voir of not less than 2.0 percent to ensure drainage and low water loss at the inlet. With the required discharge capacity, the degree of retardance, permissible velocity, and the natural slope of the exit channel known, the bottom width of the level and exit sections and the depth of the flow (Hp) can be computed using the figures in table 11. This table shows discharge per foot of width. The natural slope of the exit channel should be altered as little as possible. The selection of the degree of retardance for a given auxiliary spillway depends mainly on the height and density of the cover chosen (table 9). Generally, the retardance for uncut grass or vegetation is the one to use for capacity determination. Because protection and retardance are lower during establishment and after mowing, to use a lower degree of retardance when designing for stability may be advisable. The following examples show the use of the information in table 11: Example 1 where only one retardance is used for capacity and stability: Given: Q = 87 ft3/s (total design capacity) So = 4 percent (slope of exit channel determined from profile, or to be excavated) L = 50 ft Earth spillway is to be excavated in an erosion-resistant soil and planted with a sod-forming grass-legume mixture. After establishment, a good stand averaging from 6 to 10 inches in height is expected. Required: Permissible velocity (V) Width of spillway (b) Depth of water in the reservoir above the crest (Hp). Solution: From table 8 for sod-forming grass-legume mixtures, read permissible velocity V = 5 ft/s. From table 9 for average height of vegetation of 6 to 10 inches, determine retardance C.

31

Agriculture Handbook 590

Ponds—Planning, Design, Construction

For retardance C, enter table 11 from left at maximum velocity V = 5 ft/s. A 4 percent slope is in the slope range of 1–6 with Q of 3 ft3/s/ft. Hp for L of 50 ft = 1.4 ft. If the freeboard is 1 foot, the spillway should be constructed 29 feet wide and 2.4 feet deep. For retardance C, enter table 11 from left at maximum velocity V = 5 ft/s. A 4 percent slope is in the slope range of 1–6 with Q of 3 ft3/s/ft. Hp for L of 50 ft = 1.4 ft. If the freeboard is 1 foot, the spillway should be constructed 29 feet wide and 2.4 feet deep. Example 2 where one retardance is used for stability and another is used for capacity: Given: So = 4 percent (slope of exit channel determined from profile or to be excavated) L = 50 ft Earth spillway is to be excavated in a highly erodible soil and planted with bahiagrass. After establishment a good stand of 11 to 24 inches is expected. Required: Permissible velocity (V) Width of spillway (b) Depth of water in reservoir above the crest (Hp). Solution: From table 8 determine permissible velocity for bahiagrass in a highly erodible soil that has 8 percent slope V = 5 ft/s. From table 9, select retardants to be used for stability during an establishment period that has a good stand of vegetation of 2 to 6 inches (retardance D). Select retardance to be used for capacity for good stand of vegetation that has a length of 11 to 24 inches (retardance B). From table 11, enter from left at maximum velocity V = 5 ft/s. A slope of 6 percent is in the range for Q = 2 ft3/s/ft.
32

Then From table 11, enter q = 2 ft3/s/ft under retardance B and find Hp for L of 25 ft = 1.4 ft. If the freeboard is 1 foot, the spillway should be constructed 50 feet wide and 2.4 feet deep. Protection against erosion—Protect auxiliary spillways against erosion by establishing good plant cover if the soil and climate permit. As soon after construction as practicable, prepare the auxiliary spillway area for seeding or sodding by applying fertilizer or manure. Sow adapted perennial grasses and protect the seedlings to establish a good stand. Mulching is necessary on the slopes. Irrigation is often needed to ensure good germination and growth, particularly if seeding must be done during dry periods. If the added cost is justified, sprigging or sodding suitable grasses, such as bermudagrass, gives quick protection.

Agriculture Handbook 590

Figure 21

Inlet channel

,
Berm Hp Inlet channel Se

Plan view of earth spillways

Profile along centerline

Cross section of level portion

, , ,,,,,,, ,,,,,,, ,,,,,,
Ponds—Planning, Design, Construction

Excavated earth spillway

Level portion

Level portion

Exit channel

C L

Inlet channel

C L Exit channel

Embankment

Wing dike

C L Excavated earth spillway

(Note: Neither the location nor the alignment of the level portion has to coincide with the center line of the dam.)

Embankment

C L Optional with sod or riprap on wing dike

(Note: Use care to keep all machinery and traffic out of the spillway discharge area to protect sod.)

If both spring flow and prolonged surface flow can be expected. use table 12 or 13 to select an adequate pipe size for the barrel and riser.Agriculture Handbook 590
Ponds—Planning. The diameter of the riser must be somewhat larger than the diameter of the barrel if the tube is to flow full. It should also have enough capacity to discharge prolonged surface flow following an intense storm. This riser can also be used to drain the pond if a suitable valve or gate is attached at its upstream end (fig. no pipe smaller than 6 inches in diameter should be used for the barrel.
Figure 22
Drop-inlet pipe spillway with antiseep collar
36
. In these tables the total head is the vertical distance between a point 1 foot above the riser crest and the centerline of the barrel at its outlet end. Recommended combinations of barrel and riser diameters are shown in the tables. and table 13 is for barrels of corrugated metal pipe. The pipe should be large enough to discharge flow from springs. Because pipes of small diameter are easily clogged by trash and rodents. Construction
Pipes through the dam
Pipe spillways—Protect the vegetation in earth spillway channels against saturation from spring flow or low flows that may continue for several days after a storm. Design. Drop inlet and hood inlet pipe spillways are commonly used for ponds. snowmelt.
Drop-inlet pipe spillway—A drop-inlet consists of a pipe barrel (fig. the pipe should be large enough to discharge both. Table 12 is for barrels of smooth pipe. A pipe placed under or through the dam provides this protection. or seepage. 22) located under the dam and a riser connected to the upstream end of the barrel. The crest elevation of the entrance should be 12 inches or more below the top of the control section of the auxiliary spillway. 23). This rate of flow generally is estimated. With the required discharge capacity determined.

. .
Figure 24
Dam with hooded inlet pipe spillway
(a)
With sand-gravel filter
Hooded inlet
Pond
.. ..... usually metal. . Often a hood-inlet can be built at less cost than a drop-inlet because no riser is needed. .. . The major disadvantage of this kind of pipe spillway is that it cannot be used as a drain..
Dam
Pipe
Support for cantilever outlet (optional) Rock cover
... An antivortex device.. . Design... ........ .. Typical installations of hood inlets and details of the antivortex device are shown in figure 25. ..
Dam Hooded inlet Antiseep collar Support for cantilever outlet (optional) Pond
Pipe
Core fill
39
. The inlet end of the pipe is cut at an angle to form a hood. ..... .... . ........ .. ............ is attached to the entrance of the pipe to increase the hydraulic efficiency of the
tube. . .... .. . ..... 24). . .. .......... ... ..Agriculture Handbook 590
Ponds—Planning.
Core fill Sand-gravel filter Filter diaphragm
(b)
With antiseep collar
.... Construction
Hood-inlet pipe spillway—A hood-inlet consists of a pipe laid in the earthfill (fig. ....

Install a suitable gate or other control device and extend the drainpipe to the upstream toe of the dam to drain the pond. in either case. for irrigation. If an antiseep collar is used. use steel or plastic pipe that is l-l/2 inches in diameter. or other devices to remove the water. use steel. the three shown in figure 25 have proved the most successful. If the dam is less than 15 feet high. such as that needed to fill stockwater troughs. such as that needed for irrigation. proper installation is imperative. use two or more collars equally spaced between the fill centerline and the upstream end of the conduit when a hood-inlet pipe is used. Both types of seepage control are acceptable. For a larger rate of flow.
Drainpipes—Some state regulatory agencies require that provision be made for draining ponds completely or for fluctuating the water level to eliminate breeding places for mosquitoes. it should extend into the fill a minimum of 24 inches perpendicular to the pipe. For larger pipes. Construction
with pipe spillways for many years. This pipe is in addition to the principal spillway.Agriculture Handbook 590
Ponds—Planning. or for filling an orchard spray tank (fig. Water-supply pipes also should have watertight joints and antiseep collars or a filter and drainage diaphragm. For a small rate of flow. If a drop-inlet pipe is used. 26). For higher dams. plastic. Water-supply pipes—Provide a water-supply pipe that runs through the dam if water is to be used at some point below the dam for supplying a stockwater trough. or concrete pipe of larger diameter. Extend the pipe 6 to 10 feet beyond the downstream toe of the dam to prevent damage by the flow of water from the pipe. and a valve at its outlet end. provision for draining a pond is desirable and recommended. pumps. Whether compulsory or not. a strainer at its upper end. one antiseep collar at the centerline of the fill is enough. support the extension with a timber brace. A water-supply pipe should be rigid and have watertight joints. More fabricated materials are required for this type of installation. It permits good pond management for fish production and allows maintenance and repair without cutting the fill or using siphons. Use trash racks to keep pipes from clogging with trash and debris.
43
. Of the many kinds of racks that have been used. the antiseep collars should be equally spaced between the riser and centerline of the fill. Design.

a conservative minimum top width is 6 feet.5:1. whichever is
greater). The top width should be at least 16 feet. Design. or crevices through which water may escape at an excessive rate. an engineer should design the dam. A trench is excavated along the centerline of the dam deep enough to extend well into the impervious layer (fig. To prevent excessive seepage. investigate the nature of the rock carefully. The bottom of the trench should be no less than 8 feet wide (or the bulldozer blade width. seepage in the pervious stratum must be reduced to prevent possible failure of the dam by piping. Some foundation conditions require expensive construction measures that cannot be justified for small ponds. Cutoffs—If the dam’s foundation is overlain by alluvial deposits of pervious sands and gravels at or near the surface and rock or clay at a greater depth. Construction
Planning an earthfill dam
Foundations—You can build a safe earthfill dam on almost any foundation if you thoroughly investigate the foundation and adapt the design and construction to the conditions. fissures. and the sides no steeper than 1. A foundation. Top width and alignment—For dams less than 10 feet high. If the foundation consists of such materials. increase the top width. you need a cutoff to join the impervious stratum in the foundation with the base of the dam. Fill the trench with successive thin layers (9-inch maximum) of clay or sandy clay material. The recommended minimum top width for earth embankments of various heights is: Height of dam (ft) Under 10 11 to 14 15 to 19 20 to 24 25 to 34 Minimum top width (ft) 6 8 10 12 14
If the top of the embankment is to be used for a roadway. The most common kind of cutoff is made of compacted clayey material.Agriculture Handbook 590
Ponds—Planning. Compact each layer thoroughly at near-optimum moisture conditions before placing the next layer. consisting of or underlain by a highly plastic clay or unconsolidated material requires careful investigation and design to obtain stability. corrective measures are needed to prevent excessive seepage and possible failure. If the foundation is sand or a sand-gravel mixture and there is no impervious clay layer at a depth that can be reached economically with available excavating equipment. In some situations a curved dam align-
Figure 27
A core trench is cut on the centerline of a dam
45
. The moisture content is adequate for compaction when the material can be formed into a firm ball that sticks together and remains intact when the hand is vibrated violently and no free water appears. As the height of the dam increases. no special measures are needed except removing the topsoil and scarifying or disking to provide a bond with the material in the dam. Water impounded on a bedrock foundation seldom gives cause for concern unless the rock contains seams. If a suitable layer is at or near the surface. 27). This trench extends into and up the abutments of the dam as far as there is any pervious material that might allow seepage. Although such foundations may be stable. provide for a shoulder on each side of the roadway to prevent raveling. Where rock is in the foundation. The most satisfactory foundation consists of soil underlain at a shallow depth by a thick layer of relatively impervious consolidated clay or sandy clay. consult an engineer.

If your dam is adequately compacted in thin layers under good moisture conditions. core trench excavation. For stability. For longer ponds an engineer should determine the freeboard. Finish-grading techniques used to achieve a smooth landform transition include slope rounding and slope warping. For these dams the total settlement allowance should be about 10 percent. and is 2 feet for ponds up to a half mile long. Additional fill can be placed on the backslope and abutments of the dam. If your pond is less than 660 feet long. 28). Estimating the volume of the earthfiIl—After planning is completed. the steeper the side slopes. settlement is negligible. and settlement may range from l to 6 percent of the height of the dam. 29). To allow for settlement. the height of the dam will be adequate. are not rolled fill. The more stable the fill material. sandy clay. build earth dams somewhat higher than the design dimensions. blend the dam into surrounding natural landforms. however. Freeboard—Freeboard is the additional height of the dam provided as a safety factor to prevent overtopping by wave action or other causes. reduce the apparent size of the dam. silty sand. Curvature can be used to retain existing landscape elements. The minimum freeboard is 1. mainly during construction. clayey gravel. Slope rounding is used at the top and bottom of cuts or fills and on side slope intersections. the slopes should not be steeper than those shown in table 16. provide a freeboard of no less than l foot. Settlement allowance—Settlement or consolidation depends on the character of the materials in both the dam and the foundation and on the construction method. but they can be flatter as long as they provide surface drainage. but the foundation may settle. Construction
ment is more desirable than a straight alignment. It is the vertical distance between the elevation of the water surface in the pond when the spillway is discharging at designed depth and the elevation of the top of the dam after all
settlement. Recommended slopes for the upstream and downstream faces of dams built of various materials are shown in table 16. to achieve this landform transition. Also estimate excavation yardage in foundation stripping. silty gravel Silty clay. and any other significant excavations.Agriculture Handbook 590
Ponds—Planning. Side slopes—The side slopes of a dam depend primarily on the stability of the fill and on the strength and stability of the foundation material.5 feet for ponds between 660 and 1. and provide a natural-appearing shoreline.320 feet long. clayey silt
3:1
2:1
3:1
3:1
46
. Slope warping is used to create variety in the horizontal and vertical pitch of finished slopes (fig. After settlement. if needed. The settlement allowance for a rolled-fill dam should be about 5 percent of the designed dam height. Most pond dams less than 20 feet high. the dam is built 5 percent higher than the designed height. Design. This helps predict the cost of the dam
Table 16
Recommended side slopes for earth dams
Figure 28
Dam side slopes are curved and shaped to blend with surrounding topography
Slope Fill material Upstream Downstream
Clayey sand. The side slopes need not be uniform. Unstable materials require flatter side slopes. estimate the number of cubic yards of earthfill required to build the dam. but can be shaped to blend with the surrounding landforms (fig. Most foundations are yielding. In other words. there is no reason to expect any appreciable settlement in the dam itself. For a compacted fill dam on unyielding foundation.

The ground surface elevations at all points along the centerline of the dam where the slope changes significantly are established by the centerline profile. Probably the most efficient method of estimating the volume of earthfill is the sum-of-end-area method. or 855 square feet. The estimate of the volume of earthfill should include • volume in the dam itself including the allowance for settlement. • volume required to backfill the cutoff trench. and top width established. side slopes. find the end areas at each of these stations along the centerline in table 17. you
can obtain the settle fill height at each of these points by subtracting the ground surface elevation from the settle top elevation. assume that a dam has slopes of 3:1 on both upstream and downstream sides and a top width of 12 feet. the table shows that the end area at that point is 675 plus 180. With the settled top elevation of the dam established.. Volume estimates for dams generally are made of the required number of cubic yards of earthfill in place. Design. . The total volume of earthfill in the dam is the sum of all such segments. Construction
and serves as a basis for inviting bids and for awarding a construction contract.Agriculture Handbook 590
Ponds—Planning.
Not this
Not this
47
. For a point along the centerline where the fill is 15 feet high.. With the fill heights.
Figure 29
Finished grading techniques
(a) Slope rounding
This
(b) Slope warping
This
. A sample volume estimate illustrating the use of the sum-of-end-areas method is shown in table 18. • volume required to backfill stream channels or holes in the foundation area. and • any other volume of earthfill the contractor is required to move. The number of cubic yards of fill between two points on the centerline of the dam is equal to the sum of the end areas at those two points multiplied by the distance between these points and divided by 54. For example.

732 plus 367. and requirements for prefabricated materials. The drawings should also include a list of the estimated quantity and kind of building materials required. This 8. Unless you have all the necessary equipment. Estimate the volume of earth required to backfill the core trench. and other required excavation and add it to the estimate for the dam. you will need to employ a contractor to build the pond. Also include an estimate of additional fill to be placed on the backslope and abutments.Agriculture Handbook 590
Ponds—Planning.5 times this amount is generally necessary to have available in the borrow areas and required excavations. These drawings should show all elevations and dimensions of the dam. For example.099 cubic yards. In this example you need a minimum of 12. allows fair competition among bidders. or private consultants. • specify the quality of material and workmanship required. a minimum of 1.
[ (
)]
[Eq. Observe all land disturbance laws by including temporary protective measures during construction to minimize soil erosion and sedimentation. material quality. This provides a basis for contractors to bid on the proposed work. The specifications should • give all the information not shown on the drawings that is necessary to define what is to be done. A set of drawings and specifications shows what is to be done.0 ft Bottom width = 8. old stream channels. • prescribe how the work is to be done if such direction is required. Design. For these reasons specifications should be prepared for all ponds for which the owners award the construction contracts. and states the conditions under which the work is to be done.732 cubic yards includes only the volume of earth required to complete the dam itself. in addition to the volume shown in table 18. You may wish to receive bids from several contractors to be sure that you are getting the job done at the lowest possible cost. NRCS specialists. Construction work of the quality and standards desired will not result unless there is a clear understanding of these requirements between the owner and the contractor. or 8.099 cubic yards represents the required compacted volume. 5]
average depth bottom width length side slopes × End area = [8 + (1.5:1 Length = 177 ft Compute the volume of backfill as follows:
End Area = w + z × d d a
other areas requiring backfill. The construction and material specifications state the extent and type of work. Assistance in preparing drawings and specifications is available from your local soil conservation district. and any other pertinent information.5 x 4)]4 = 56 ft2
Volume = 56 × 177 2 = 367 yd3 27
Add this to the volume required for the dam and the total volume is 7. assume that.0 ft Side slopes = 1. the location and dimensions of the principal spillway and other planned appurtenances. Drawings and specifications—Record on the engineering drawings all planning information that would affect the construction of the dam. the dimensions and extent of the cutoff trench and
52
. 4]
Volume =
where: d = w = l = z =
l ( End area × 1)
27
[Eq. there is a cutoff trench to be backfilled.148 cubic yards available to construct the dam. The dimensions of the trench are: Average depth = 4. site specific details. To account for shrinkage resulting from compaction. Construction
The sample volume estimate of 7. and • define the method of measurement and the unit of payment for the various items of work that constitute the whole job.

If fill material must be obtained from a borrow area. filter and drainage diaphragm or antiseep collars. Staking transmits the information on the drawings to the job site. Minimal clearing conserves site character and minimizes the difficulty and expense of reestablishing vegetation. and the cost is generally less in the long run than it is for dams built carelessly. Set stakes to show the centerline location of the principal spillway after foundation preparation has reached the point at which the stakes will not be disturbed. first stake the centerline and then set cut and slope stakes along the lines of intersection of the spillway side slopes with the natural ground surface. the auxiliary spillway site. With additional stakes. from the earth spillway and borrow areas.
Building the pond
Attention to the details of construction and adherence to the drawings and specifications are as important as adequate investigation and design. This information locates the work and provides the lines. Clearing and grubbing—Clear the foundation area and excavated earth spillway site of trees and brush. and elevations required for construction in accordance with the drawings. Construction
Staking for construction
Each job must be adequately and clearly staked before construction is started. Locate the pipe where it will rest on a firm foundation. Confine clearing limits to the immediate construction areas to avoid unnecessary disturbance. burying under 2 feet of soil. grade. This allows the borrow area to drain readily and marks the limits of construction. Adherence to specifications and prescribed construction methods becomes increasingly important as the size of the structure and the failure hazards increase. If so. drainage gate.
Figure 30
A tree well preserves vegetation
53
. In the pond area. fill the holes by placing suitable material in layers and compact each layer by compacting or tamping. Cut trees and brush as nearly flush with the ground as practicable and remove them and any other debris from the dam site. The areas to be cleared generally consist of the dam site. and other appurtenances. as indicated by soil borings. Good construction is important regardless of size. To locate the dam. you must determine if the tree roots extend into pervious material and if the resultant holes will cause excessive seepage. (Generally this has been done during the initial planning survey. This provides a base line from which clearing limits can be established. To locate the earth auxiliary spillway. mark the location of the riser.) Then set the fill and slope stakes upstream and downstream from the centerline stakes to mark the points of intersection of the side slopes with the ground surface and to mark the work area limits of construction. The quality and appearance of the completed job reflect the care used in staking. All material cleared and grubbed from the pond site. and from the site of the dam itself should be disposed of. set stakes along its centerline at intervals of 100 feet or less. The staking should be done by an engineer or other qualified person. Set cut stakes to indicate the depth to which the contractor can excavate to stay within the limits of suitable material. Mark each area clearly with an adequate number of stakes. such as a sanitary landfill. and the area over which water is to be impounded. Should you or your contractor elect to uproot the trees with a bulldozer. locate the proposed water line with a level and surveying rod. This can be done by burning. Careless and shoddy construction can make an entirely safe and adequate design worthless and cause failure of the dam. In some states this is required by statute. or burying in a disposal area. Design. Mark the stakes to show cuts from the top of the stakes to the grade elevation of the pipe.Agriculture Handbook 590
Ponds—Planning. the borrow area. Consider the contractor’s wishes in staking so that he can make the most effective use of the stakes. this area must be clearly marked. outlet structures. These stakes also establish the height of the dam.

Fill all holes in the foundation area.to 2-foot layer of graded fill over their root systems or they can be root-pruned in excavated areas.Agriculture Handbook 590
Ponds—Planning. . excavating and backfilling the cutoff trench. The topsoil should be stockpiled temporarily for later use on the site. This operation is best performed by using a tractor-pulled or self-propelled wheeled scraper. Feathering can be accomplished by selective clearing. boulders. 32). and topsoil from the entire area over which the embankment is to be placed.
Figure 31 Irregular clearing around the pond helps create a natural appearing edge
This Irregular clearing edge Existing trees Pond Not this Existing trees Straight clearing edge Pond
After filling the holes.. Often the depths shown on the drawings are only approximate.
.. Density and height of vegetation can be increased progressively from the water’s edge to the undisturbed vegetation (fig. or both. Construction
Removing all vegetation within the construction limits is not always necessary.. Selected groupings of desirable plants can be kept. installation of new plants.. Trees and shrubs can often survive a 1. 30). Use the same method of placement and compaction as used to build the dam. and excavating and backfilling existing stream channels. bottom width. Dig the cutoff trench to the depth. If the foundation has an adequate layer of impervious material at the surface or if it must be blanketed by such a layer. both natural and those resulting from grubbing operations. and side slopes shown on the drawings.. . Remove sod.
Preparing the foundation—Preparing the foundation includes treating the surface..
Clearing limits should be irregular to create a naturalappearing edge and open area (fig.. Where necessary use hand or power tampers in areas not readily accessible to other compacting equipment. you
Figure 32
Feathering vegetation at the pond's edge makes a natural transition with existing vegetation
This Selective clearing and/or plantings Minimum clearing limits Clearing limits Not this
Existing trees
Existing trees
Pond Selective clearing and/or planting creates a natural appearance Lack of transition treatment creates an unnatural edge
54
. Roughly level the surface with a disk harrow and then compact it so that the surface materials of the foundation are as well compacted as the subsequent layers of the fill. . you can eliminate the cutoff trench. . Further transition with vegetated surroundings can be accomplished by feathering clearing edges. thoroughly break the ground surface and turn it to a depth of 6 inches. Tree wells and raised beds can also be used to retain vegetation (fig. with suitable fill material from borrow areas.... Design.. 31).

grades. Material removed from the trench can be placed in the downstream third of the dam and compacted in the same manner as the earthfill if the material is free of boulders. organic matter. If the channels are parallel to the centerline. Backfill these channels as recommended for the cutoff trench. and side slopes shown on the drawings and staked at the site. If it becomes necessary to fill low places or depressions in the channel bottom caused by undercutting the established grade. Place the backfill material in thin layers and compact it by the same methods used to build the dam. filter and drainage diaphragm or antiseep collars. stumps. leave the side slopes no steeper than 1:1. slope back. The same procedure applies to all other pipes or conduits. and widen stream channels that cross the embankment foundation. roots. Excavating the earth spillway—The completed spillway excavation should conform as closely as possible to the lines. Design. Leave side slopes
of the excavated channels no steeper than 3:1 when the channels cross the embankment centerline. roots. Before backfilling operations are attempted. This is often necessary to remove all stones. bottom width. and other mechanical components of the dam to the lines and grades shown on the drawings and staked at the site. Some material high in clay content takes up more than twice its own weight of water and becomes a soggy mass. riser (if applicable). gravel. sediment. A dragline excavator and a tractor-pulled or selfpropelled wheeled scraper are the most satisfactory equipment for excavating cutoff trenches. To minimize the danger of cracks or openings at the joints caused by unequal settlement of the foundation. and other objectionable material.Agriculture Handbook 590
Ponds—Planning. Install pipes and filter and drainage diaphragm or antiseep collars and tamp the selected backfill material around the entire structure before placing the earthfill for the dam.
55
. Construction
need to inspect the completed trench before backfilling to be sure that it is excavated at least 12 inches into impervious material throughout its entire length. and any other objectionable material that could interfere with proper bonding of the earthfill with the foundation. organic matter. trash rack. Backfill the cutoff trench to the natural ground surface with suitable fill material from designated borrow areas. Deepen. Such clay puddled in the cutoff of a dam may require many years to become stable. pump all free water from the cutoff trench. sand. Also. in drying it contracts and may leave cracks that can produce a roof of the overlying impervious earthfill section and provide passageways for seepage through the dam. place all pipes and other conduits on a firm foundation. Leave the channel bottom transversely level to prevent meandering and the resultant scour within the channel during periods of low flow. Installing the pipe spillway—Install the pipe. fill them to the established grade by placing suitable material in 8-inch layers and compacting each layer under the same moisture conditions regardless of the placement in or under the embankment.

the moisture content is adequate for compaction. If the material varies in texture and gradation. Design. For fill placement around risers. boulders. Equipment that has rubber tires can be routed so each layer is sufficiently covered by tire tracks. Selected backfill material should be placed in the core trench and around pipes and antiseep collars. Do not place fill in standing water. Begin placing fill material at the lowest point and bring it up in horizontal layers. roots.
Figure 33
The sod and topsoil in a pond construction area can be stockpiled for later use
56
. special equipment. the horizontal layers should be
approximately 4 inches thick. and upstream parts of the dam. stones more than 6 inches in diameter. Do not use frozen material or place fill material on frozen foundations. such as sheepsfoot rollers. brush. The material should be free of sod. use the more impervious (clay) material in the core trench. sod. Construction equipment can be used to compact earthfill in an ordinary pond dam. Laboratory tests of the fill material and field testing of the soil for moisture and compaction may be necessary for large ponds or special conditions. Construction
Building the dam—Clear the dam and spillway area of trees. Get suitable fill material from previously selected borrow areas and from sites of planned excavation. longitudinal to the centerline of dam. stumps. when used. This will help when vegetation is established. The moisture content is adequate for compaction when the material can be formed into a firm ball that sticks together and remains intact when the hand is vibrated violently and no free water appears. For dams over 20 feet high.Agriculture Handbook 590
Ponds—Planning. should be used. 33). center. approximately 6 inches thick. The sod and topsoil can be stockpiled and used later to cover the dam and spillway (fig. The material should be compacted by hand tamping or manually directed power tampers around pipes. and rubbish. and drainage diaphragms. and any material that could prevent the desired degree of compaction. pipes and filter. If the material can be formed into a firm ball that sticks together.

Bore test holes at intervals over the site to determine the existence and physical characteristics of the water-bearing material. If an excavated pond is to be fed from a water-bearing sand or a sand-gravel layer. Avoid soil underlain by limestone containing crevices. their compactness. They are. This depth seldom exceeds 20 feet. The seepage indicates what to expect of a pond excavated in the same kind of material. but may increase the construction cost considerably. or channels. Thoroughly investigate sites proposed for aquifer-fed excavated ponds. Excavated ponds fed by surface runoff can be located in almost any kind of topography. enough impervious soil at the site is essential to avoid excess seepage losses. You can get some indication of permeability by filling the test holes with water. the layer must be at a depth that can be reached practically and economically by the excavating equipment. Design. usually layers of sand and gravel. their relative safety from floodflow damage. The ease with which they can be constructed. After the pond is filled. Check the rate at which the water rises in the test holes. Excavated ponds fed by ground water aquifers can be located only in areas of flat or nearly flat topography. excess runoff escapes through regular drainageways. Check the test hole during drier seasons to avoid being misled by a high water table that is only temporary. as for irrigation. most satisfactory and most commonly used in areas of comparatively flat.Agriculture Handbook 590
Ponds—Planning.
Soils
If an excavated pond is to be fed by surface runoff. but well-drained terrain. A rapid rate of rise indicates a high-yielding aquifer. The general location of an excavated pond depends largely on the purpose or purposes for which the water is to be used and on other factors discussed previously in this handbook. They are best suited to locations where the demand for water is small. Construction
Excavated ponds
Excavated ponds are the simplest to build in relatively flat terrain. The water-bearing layer must be thick enough and permeable enough to yield water at a rate that satisfies the maximum expected demand for water and overcomes evaporation losses. If water is removed from the pond at a rapid rate. and their low maintenance requirements make them popular in many sections of the country.
clay extends to adequate depths generally are satisfactory. Avoid sites where the soil is porous or is underlain by strata of coarse-textured sand or sand-gravel mixtures unless you are prepared to bear the expense of an artificial lining. the water can be expected to return to its normal level within a short time after removal has ceased. A pond can be located in a broad natural drainageway or to one side of a drainageway if the runoff can be diverted into the pond. From an economic standpoint. Because their capacity is obtained almost solely by excavation. however. The vertical distance between this level and the ground surface determines the volume of overburden or excavation needed that does not contribute to the usable pond capacity. The performance of nearby ponds that are fed by runoff and in a similar soil is a good indicator of the suitability of a proposed site. sinks. A slow rate of rise in the test holes indicates a low-yielding aquifer and a slow rate of recovery in the pond. this vertical distance between water level and ground surface generally should not exceed 6 feet. Because excavated ponds can be built to expose a minimum water surface area in proportion to their volume. Supplement such observations of existing ponds by boring enough test holes at intervals over the proposed pond site to determine accurately the kind of material there. One is fed by surface runoff and the other is fed by ground water aquifers. The most desirable sites are where fine-textured clay and silty clay extend well below the proposed pond depth. Sites where sandy
57
. their practical size is limited. The low point of a natural depression is often a good location. they are advantageous in places where evaporation losses are high and water is scarce. If possible. they should be located where the permanent water table is within a few feet of the surface. The specific location is often influenced by topography. Some ponds may be fed from both of these sources. The water level in the test holes indicates the normal water level in the completed pond. Two kinds of excavated ponds are possible.

the overfall from the ditch bottom to the bottom of the pond can create a serious erosion problem unless the ditch is protected.5 foot above the top of the pipe at the upstream end. the combined capacity should equal or exceed the estimated peak rate of runoff. The rectangular shape is popular because it is simple to build and can be adapted to all kinds of excavating equipment. you should provide a desilting area or filterstrip in the drainageway immediately above the pond to remove the silt before it enters the pond.Agriculture Handbook 590
Ponds—Planning. After you prepare a seedbed. The extended part of the pipe or pipes can be cantilevered or supported with timbers. A pond can be excavated in a rectangular form and the edge shaped later with a blade scraper to create an irregular configuration (fig. Scouring can occur in the side slope of the pond and for a considerable distance upstream in the ditch. As the water flows through the vegetation. however. Pipe diameter 1/ (in) 15 18 21 24 30 36 42 48 54 60 Pond inflow Q (ft3/s) 0 to 6 6 to 9 9 to 13 13 to 18 18 to 30 30 to 46 46 to 67 67 to 92 92 to 122 122 to 157
In areas where a considerable amount of silt is carried by the inflowing water. Follow the procedures for planning the spillway and provide protection against erosion as discussed in the Excavating the earth spillway section. If surface runoff must enter an excavated pond through a channel or ditch rather than through a broad shallow drainageway.
Figure 34
Geometric excavation graded to create more natural configuration
1/ Based on a free outlet and a minimum pipe slope of 1 percent with the water level 0. For this reason. The resulting sediment tends to reduce the depth and capacity of the pond. You need an auxiliary spillway to pass excess storm runoff around the small dam. where the resulting shape would be in sharp contrast to surrounding topography and landscape patterns. The capacity of an excavated pond fed by surface runoff is determined largely by the purpose or purposes for which water is needed and by the amount of inflow that can be expected in a given period. Protect the slope by placing one or more lengths of rigid pipe in the ditch and extending them over the side slope of the excavation.
Planning the pond
Although excavated ponds can be built to almost any shape desired. 34). Ponds excavated in areas of flat terrain generally require constructed spillways. fertilize. Rectangular ponds should not be constructed. a rectangle is commonly used in relatively flat terrain. Construction
Spillway and inlet requirements
If you locate an excavated pond fed by surface runoff on sloping terrain. The diameter of the pipes depends on the peak rate of runoff that can be expected from a 10-year frequency storm. This area or strip should be as wide as or somewhat wider than the pond and 100 feet or more long. the silt settles out and the water entering the pond is relatively silt free. The required capacity of an excavated pond fed by an underground waterbearing layer is difficult to determine because the rate of inflow into the pond can seldom be estimated accurately. Design. If you need more than one pipe inlet. and seed the area to an appropriate mix of grasses and forbs. you can use a part of the excavated material for a small low dam around the lower end and sides of the pond to increase its capacity.
Excavated area
Final edge
58
. the pond should be built so that it can be enlarged if the original capacity proves inadequate.

The maximum depth is generally determined by the kind of material excavated and the type of equipment used. Estimating the volume—After you have selected the dimensions and side slopes of the pond.
Regardless of the intended use of the water. For example. the most important is depth. provide a ramp with a flat slope (4:1 or flatter) for access. Construction
Selecting the dimensions—The dimensions selected for an excavated pond depend on the required capacity. To prevent sloughing. This estimate determines the cost of the pond and is a basis for inviting bids and for making payment if the work is to be done by a contractor. If an excavated pond is fed from ground water. these flat slopes are necessary if certain types of excavating equipment are used. The minimum length of the pond is determined by the required pond capacity. Of the three dimensions of a pond. If the pond is to be used for watering livestock. 6]
where: V = volume of excavation (yd3) A = area of the excavation at the ground surface (ft2) B = area of the excavation at the mid-depth (1/2 D) point (ft2) C = area of the excavation at the bottom of the pond (ft2) D = average depth of the pond (ft2) 27 = factor converting cubic feet to cubic yards
Figure 35
Typical sections of an excavated pond
Total length 172 ft Total width 88 ft A B A 136 ft Length 100 ft Longitudinal section (not to scale) 6 ft 6 ft Depth 12 ft B 64 ft 6 ft 6 ft Depth 12 ft
2:1
4:1
48 ft
2:1
2:1
C 24 ft
C 24 ft
Width 40 ft Cross section (not to scale)
24 ft
59
. The type and size of the excavating equipment can limit the width of an excavated pond. the side slopes of the pond are generally no steeper than the natural angle of repose of the material being excavated.Agriculture Handbook 590
Ponds—Planning. 35). the length of the boom usually determines the maximum width of excavation that can be made with proper placement of the waste material. The volume of excavation required can be estimated with enough accuracy by using the prismoidal formula:
V=
( A + 4B + C) ×
6
D 27
[Eq. Design. it should be deep enough to reach well into the waterbearing material. estimate the volume of excavation required. Tractor-pulled wheeled scrapers and bulldozers require a flat slope to move material from the bottom of the excavation. but for most ponds the side slopes are 1:1 or flatter (fig. if a dragline excavator is used. This angle varies with different soils. All excavated ponds should have a depth equal to or greater than the minimum required for the specific location.

of 12 feet. Do not stack waste material in a geometric mound.. If you stack the material.
Waste material poorly shaped. The side slope at the ramp end is 4:1. The value assigned to the depth D is the actual depth of the water in the pond rather than depth of excavation. a bottom width.× 100×=100000 .
Correct disposal of waste material
This Not this
. September 2.996 cubic yards times 0. and vegetated blends into surrounding landscape. 952
Then
V= 53. The sample procedure is used to compute the volume of water that can be stored in the pond if the normal water level is below the ground surface. 816 A . To convert to gallons.996 cubic yards multiplied by 201. Design.Agriculture Handbook 590
Ponds—Planning. 000 C = 40 4. 36). . assume a pond with a depth. Adequate placement prolongs the useful life of the pond.
60
. L. The waste material can be stacked. place it with side slopes no steeper than the natural angle of repose of the soil. Landscape Design: Ponds.97 equals 807. . 3. Avoid interrupting the existing horizon line with the top of the waste mound (fig. and facilitates maintenance and establishment of vegetation. 2. the volume of water that can be stored in the pond is 3. place it so that its weight does not endanger the stability of the side slopes and rainfall does not wash the material back into the pond. and the remaining slopes are 2:1. and other circumstances warrant. the waste material may be the most conspicuous feature in the landscape. Because many excavated ponds are in flat terrain. 136 88 172 172 . or removed from the site as conditions.
A = A =×88 × = 15=136.00061963. 952 12 yd3 × = 3.. graded. 4B ( A + 4 B + C ) =( 53+952 + C ) = 53. or 2. = 4
If the normal water level in the pond is at the ground surface.. 996 yd 3 6 27
(
)
˜ C = 40. of 100 feet as shown in figure 35. If you do not remove the waste material from the site. is computed as follows:
A summary of methods for estimating the volume of an excavated pond is provided in appendix A. but shape and spread it to blend with natural landforms in the area. V. Construction
As an example. 1988. unvegetated. W.. D.
Figure 36
Waste material properly shaped. This summary information is reprinted from NRCS (formerly SCS) Landscape Architecture Note No.072 gallons. improves its appearance. and a bottom length. The volume of excavation. nature of the material..48 acre-feet. of 40 feet. 15
4 B = 4 64 × 136 = 34. spread. and interrupting the horizon line appears unnatural. Waste material—Plan the placement or disposal of the material excavated from the pond in advance of construction operations.

If state or county highway maintenance crews need such material. Tractor-pulled wheeled scrapers. if the length of push is long. can be used to good advantage. you may be able to have them remove it. Construction
Waste material can also be located and designed to be functional. 37). particularly if the waste material is to be shaped. Design. not carry it. It can screen undesirable views. In high-rainfall areas and in areas where the water table is within the limits of excavation. buffer noise and wind. you generally need other kinds of equipment to stack or spread the waste material and shape the edge to an irregular configuration. a dragline excavator is commonly used because it is the only kind of equipment that operates satisfactorily in any appreciable depth of water. using these machines is expensive. Excavation and placement of the waste material are the principal items of work in building this type pond. or improve the site’s suitability for recreation (fig. you can use almost any kind of available equipment. If you use a dragline excavator. Graders. In shaping the material. a dragline is normally used to excavate the basic pond.. however.
Building the pond
Clear the pond area of all undesired vegetation. In low-rainfall areas where water is unlikely to accumulate in the excavation. Perhaps the most satisfactory method of handling waste material is to remove it from the site. For ponds fed by ground water aquifers. Complete removal.Agriculture Handbook 590
Ponds—Planning. Bulldozers are most commonly used. Bulldozers can only push the excavated material. Mark the outside limits of the proposed excavation with stakes. . the toe of the fill must be at least 12 feet from the edge of the pond.
The kind of excavating equipment used depends on the climatic and physical conditions at the site and on what equipment is available. These banks can also reduce evaporation losses by breaking the force of prevailing winds across the pond. is expensive and can seldom be justified unless the material is needed nearby.
Figure 37
New plantings Waste material
Waste material and plantings separate the pond from a major highway
61
.
. On the stakes indicate the depth of cut from the ground surface to the pond bottom.. Waste material can sometimes be used advantageously for filling nearby low areas in a field or in building farm roads. dragline excavators. Excavate and place the waste material as close as possible to the lines and grades staked on the site. and track-type tractors equipped with a bulldozer blade are generally used. either tractor-pulled or self-propelled. In the Great Plains you can place the waste material on the windward side of the pond to serve as a snow fence for collecting drifts in the pond.

To prevent excessive seepage. crevices. The procedure is simple. or channels. exposes highly pervious material. Selecting a poor site is often the result of inadequate site investigations and could have been avoided. usually to provide material for the embankment. Its use. or similar equipment. In this case the original pond design must include plans for reducing seepage by sealing (fig. Scarify the soil to a depth of 16 to 18 inches with a disk. reduce the permeability of the soils to a point at which losses are insignificant or at least tolerable. The method depends largely on the proportions of coarse-grained sand and gravel and of fine-grained clay and silt in the soil. pulverizer. In some places no satisfactory site is available. Clear the pond area of all trees and other vegetation. This can be avoided by carefully selecting the source of embankment material. is limited to these soil conditions as well as by the depth of water to be impounded. however. or rock containing cracks. and similar areas with impervious material. tight layer with four to six passes of a sheepsfoot roller in the same manner as for compacting earth embankments. Remove all rocks and tree roots. one where the soils in the impounding area are too permeable to hold water. but the need for water is great enough to justify using a site that is somewhat less than satisfactory. This is the least expensive method of those presented in this handbook.Agriculture Handbook 590
Ponds—Planning. increase the thickness of the compacted seal proportionately if the depth of
Figure 38
Disking in chemical additive to seal a pond
62
. Construction
Compaction
Sealing the pond
Excessive seepage in ponds is generally because the site is poor. such as sand. crevices. Roll the loosened soil under optimum moisture conditions in a dense.
Some pond areas can be made relatively impervious by compaction alone if the material contains a wide range of particle sizes (small gravel or coarse sand to fine sand) and enough clay (10 percent or more) and silt to effect a seal. rototiller. Make the compacted seal no less than 12 inches thick where less than 10 feet of water is to be impounded. 38). Because seepage losses vary directly with the depth of water impounded over an area. gravel. In some places excessive removal of the soil mantle during construction. Design. Fill all stump holes. that is.

assume a pond with a depth. which is assumed to be 0. Thickness of the blanket depends on the depth of water to be impounded. The minimum compacted thickness is 12 inches for all depths of water under 10 feet. Therefore.
where: d = thickness of compacted seal k = coefficient of permeability of compacted seal. Design. Mixed in the correct proportions with well-graded coarse-grained material.4 ft
If soil samples were taken and permeability tests were performed on the material of the compacted seal at the density it is to be placed. Calculate the required minimum thickness of the compacted seal. The requirements for good blanket material are about the same as those described for earth embankments. On drying.
d=
(
k× H v− k
)
[Eq. Bentonite is a fine-textured colloidal clay. Compact the soils in two or more layers not exceeding 9 inches uncompacted over the area.003 fpd unless testing is done H = water depth v = allowable specific discharge which is assumed to be 0. thoroughly compacted and then saturated. at complete saturation. When wet it absorbs several times its own weight of water and.
Bentonite
Adding bentonite is another method of reducing excessive seepage in soils containing high percentages of coarse-grained particles and not enough clay.Agriculture Handbook 590
Ponds—Planning. use the assumed values for k and v. Using the preceding equation:
d=
0. Use rock riprap or other suitable material to protect areas where the waterflow into the pond is concentrated. Blanket the entire area over which water is to be impounded as well as the upstream slope of the embankment. Construction is similar to that for earth embankments. but lacking enough clay to prevent excessive seepage. Remove and stockpile the top layer or layers while the bottom layer is being compacted. H.028 fpd − 0.028 fpd unless otherwise specified As an example. No soil samples were taken for laboratory testing.003 fpd
= 1. a thickness less than what was calculated may be possible. bentonite returns to its original volume leaving cracks. sealing with bentonite usually is not recommended for ponds in which the water level is expected to fluctuate widely. A laboratory analysis of the pond area material to determine the rate of application is essential. Spread a cover of gravel 12 to 16 inches thick over the blanket below the anticipated high water level. of 12 feet. Remove all trees and other vegetation and fill all holes and crevices before hauling earth material from the borrow area to the pond site in tractor-pulled wheeled scrapers or similar equipment. the particles of bentonite swell until they fill the pores to the point that the mixture is nearly impervious to water. Increase this thickness by 2 inches for each foot of water over 10 feet and above.003 fpd × 12 ft 0. by four to six passes of a sheepsfoot roller before placing the next layer. Spread the material uniformly over the area in layers 6 to 8 inches thick. 7]
material containing at least 20 percent clay.
63
Clay blankets
Pond areas containing high percentages of coarsegrained soils. Construction
water impounded exceeds 10 feet or more. Protect clay blankets against cracking that results from drying and against rupture caused by freezing and thawing. The blanket should consist of a well-graded
. the minimum thickness should never be less than 12 inches. You can usually obtain material for the blanket from a borrow area close enough to the pond to permit hauling at a reasonable cost. Compact each layer thoroughly. Without knowing whether the soil underlying the compacted layer will act as a filter for the compacted layer. however. The thickness of the compacted seal can be determined using equation 7. under optimum moisture conditions. For this reason. can be sealed by blanketing. swells as much as 8 to 20 times its original volume.

Soda ash. Design. can also be used. If the source is far from the pond site. or by hand broadcasting. Mix the dispersing agent with the surface soil and then compact it to form a blanket. the soil is said to be aggregated. Chemical treatment is not effective in coarse-grained soils. A mulch of straw or hay pinned to the surface by the final passes of the sheepsfoot roller gives this protection. Thickness of the blanket depends on the depth of water to be impounded. A rototiller is best for this operation. If the area is too wet. Then compact the area with four to six passes of a sheepsfoot roller. The chemicals used are called dispersing agents. tetrasodium pyrophosphate and sodium tripolyphosphate are most effective.05 to 0. the thickness should be increased at the rate of 2 inches per foot of water depth from 10 feet and above. Use rock riprap or other suitable material to protect areas where water inflow into the treated area is concentrated. If the soil is too wet. The dispersant should be finely granular. This dispersed structure reduces soil permeability. and the material may become too wet to handle. If considerable time elapses between applying the bentonite and filling the pond. Cover rock outcrops and other exposed areas of highly permeable material with 2 to 3 feet of finegrained material.33 pound per square foot. As with other methods. technical grade 99 to 100 percent sodium carbonate.
64
. The moisture level should be optimum for good compaction. the compacted blanket should be at least 12 inches thick. the cost may prohibit the use of bentonite. 100 sieve. If the soil is too dry. add water by sprinkling. This generally is an uncompacted thickness of approximately 8 to 9 inches. postpone sealing until moisture conditions are satisfactory. This rate usually is 1 to 3 pounds per square foot of area. clear the pond area of all vegetation. Applying small amounts of certain chemicals to these porous aggregates may result in collapse of the open structure and rearrangement of the clay particles. or honeycomb structure. The soil moisture level in the area to be treated should be near the optimum level for good compaction. If it is too dry. Thoroughly compact this material. locate the nearest satisfactory source of bentonite and investigate the freight rates.
The soils in the pond area should contain more than 50 percent fine-grained material (silt and clay) and at least 15 percent clay for chemical treatment to be effective. It can be applied with a seeder. add water by sprinkling. Construction
Before selecting this method of sealing a pond. the success or failure of the seal may depend on the thickness and compaction of this initial blanket.
Chemical additives
Because of the structure or arrangement of the clay particles. and sodium chloride at a rate of 0.20 pound per square foot. postpone treatment. Apply the dispersing agent uniformly over the pond area at a rate determined by laboratory analysis. drill. If these particles are arranged at random with end-to-plate or end-to-end contacts. Soda ash is applied at a rate of 0.10 pound per square foot. Polyphosphates release water from soil.Agriculture Handbook 590
Ponds—Planning. Investigate it before applying bentonite. Sodium polyphosphates generally are applied at a rate of 0. Although many soluble salts are dispersing agents.10 to 0. but a disk or similar equipment can be used. they form an open. For greater depths. fertilizer spreader. In cavernous limestone areas. For water less than 10 feet deep. Thoroughly mix the bentonite with the surface soil to a depth that will result in a 6-inch compacted layer. 30 sieve and less than 5 percent passing a No. Clear the area to be treated of all vegetation and trash. and cover and compact areas of exposed gravel with suitable fill material. sodium polyphosphates and sodium chloride (common salt) are most commonly used. Spread the bentonite carefully and uniformly over the area to be treated at the rate determined by the laboratory analysis. Fill all holes or crevices. seepage is often excessive in fine-grained clay soils.20 to 0. Of the sodium polyphosphates. The soil moisture level in the area to be treated is important. A laboratory analysis of the soil in the pond area is essential to determine which dispersing agent will be most effective and to determine the rate at which it should be applied. porous. protecting the treated area against drying and cracking may be necessary. with at least 95 percent passing a No.

In these areas a minimum 9-inch cover should be used on all types of flexible membranes. Butyl-rubber membranes need not be covered except in areas traveled by livestock. Be extremely careful to avoid punctures. Some plants may penetrate both vinyl and polyethylene film. Polyethylene should have up to 10 percent slack. cover it with a cushion layer of fine-textured material before placing the lining. Protect the treated blanket against puncturing by livestock. Construction
Thoroughly mix the dispersing agent into each 6-inch layer to be treated. butyl-rubber membranes. but slack. Black polyethylene films are less expensive and have better aging properties than vinyl. The bottom 3 inches of cover should be no coarser than silty sand. johnsongrass. allowing a 6-inch overlap for seaming. is more resistant to impact damage and is readily seamed and patched with a solvent cement. especially the side slopes. Fill all holes and remove roots. Vinyl.to 18-inch blanket of gravel or other suitable material to protect it against erosion. Thin films of these materials are structurally weak. on the other hand. Polyethylene. sharp stones. and other plants having high penetration are present. and asphalt-sealed fabric liners are gaining wide acceptance as linings for ponds because they virtually eliminate seepage if properly installed. rototiller. pulverizer. If the material is stony or of very coarse texture. You can use a disk.
65
. or similar equipment. Several good chemical sterilizers are available commercially. Operating the mixing equipment in two directions produces best results. If nutgrass. Clear the pond area of all undesired vegetation. Use riprap or other suitable material in areas where inflow into the pond is concentrated. vinyl. or other objects that might puncture the film. Polyethylene can be joined or patched with a special cement. Anchor the top of the lining by burying it in a trench dug completely around the pond at or above the normal water level. The anchor trench should be 8 to 10 inches deep and about 12 inches wide.
All plastic membranes should have a cover of earth or earth and gravel not less than 6 inches thick to protect against punctures.Agriculture Handbook 590
Ponds—Planning. Design. quackgrass. Vinyl and butyl-rubber linings should be smooth. Thoroughly compact each chemically treated layer with four to six passes of a sheepsfoot roller. Lay the linings in sections or strips.
Waterproof linings
Using waterproof linings is another method of reducing excessive seepage in both coarse-grained and finegrained soils. but if not broken or punctured they are almost completely watertight. should be sterilized. Cover the area near the high-water line with a 12. Sterilization is not required for covered butyl-rubber linings 20 to 30 mils thick. the subgrade.

The choice of method depends on whether the normal pool level remains fairly constant or fluctuates. Grade and shape the banks or side slopes of borrow pits to a slope that permits easy mowing. or a high water table. Additional information about these and other soil bioengineering systems is in Part 650. but also conserves moisture and provides conditions favorable for germination and growth. water is withdrawn periodically during the growing season and the water level may fluctuate from normal pool level to near pond bottom one or more times each year. or one of several commercially manufactured materials may be desirable. and allows the graded area to blend with the landscape. and mulching procedures. screening. Leave borrow pits in condition to be planted so that the land can be used for grazing or some other purpose. rates of fertilization. and any other source of damage.
Wave action
Several methods are available to protect the upstream face of a dam against wave action. Ponds without this protection may be short lived. brushmattresses. If construction is completed when the soils are too dry for the seeds to germinate.
Protecting the pond
Construction of the pond is not complete until you have provided protection against erosion. Trees and shrubs that remain or those planted along the shoreline will be subject to flooding. or small plants from rainfall damage.
66
. Berms—If the water level in the pond is expected to remain fairly constant. The ability to tolerate such drastic changes varies greatly among species. a berm 6 to 10 feet wide located at normal pool level generally provides adequate protection against wave action. Mulching with a thin layer of straw. Fertilize and seed with mixtures of perennial grasses and forbs appropriate for local soil and climatic conditions. wave action. climate control. preferably no steeper than 4:1. This is generally done by disking or harrowing.Agriculture Handbook 590
Ponds—Planning. It is often desirable to establish vegetation to make the borrow area compatible with undisturbed surroundings. and the borrow areas as well as other disturbed surfaces can be protected from erosion by establishing a vegetative community of appropriate species. In many areas the exposed surface of the dam. shrubs. irrigate the soils to ensure prompt germination and continued growth. live fascines. asphalt. Design. The systems best suited to these conditions include live stakes. Mulching not only protects the newly prepared seedbed. The vegetation should be able to survive under prevailing conditions with minimum maintenance. The slope above the berm should be protected by vegetation. Grade all areas or pits from which borrow material has been obtained so they are well drained and do not permit stagnant water to accumulate as breeding places for mosquitoes. The degree of protection required also influences the choice of method. An irrigation pond is an example of the latter. wave action. seeds. Their functions include erosion control. Soil bioengineering systems should be employed to establish woody vegetation where appropriate on the shorelines of ponds. In these ponds. The berm should have a downward slope of about 6 to 12 inches toward the pond. A planting plan indicating the species and rate of application of the vegetation can be helpful in achiev-
ing the desired results. fodder. Prepare a seedbed as soon after construction as practicable. space definition. and wildlife habitat. Engineering Field Handbook. contact the local representatives of the Natural Resources Conservation Service or the county agent. chapters 16 and 18. and the cost of maintenance is usually high. and forbs should be planted during or soon after construction. Construction
Establishing vegetation
Trees. For information on recommended plants and grass mixtures. Flood tolerance and resistance to wave action depend on root density and the ability to regenerate from exposed roots. the auxiliary spillway. trampling by livestock. old hay. live siltation. Native varieties are preferred for new plantings. grasses. and reed clumps.

Design. Booms do not give as much protection as some other methods described. but less labor. Riprap—Rock riprap is an effective method of control if a high degree of protection is required or if the water level fluctuates widely. Not all ponds used for watering livestock need to be fenced. Fencing provides the protection needed to develop and maintain a good plant cover on the dam. It enhances clean drinking water and eliminates damage or pollution by livestock. The marshy vegetation needed around ponds for satisfactory wildlife food and cover does not tolerate much trampling or grazing. Riprap is dumped directly from trucks or other vehicles or is placed by hand. A rancher with many widely scattered ponds and extensive holdings must have simple installations that require minimum upkeep and inspection. Fencing critical parts of livestock watering ponds. frame them together to act as a unit. If riprap is not continuous to the upstream toe. For best results place the boom so that it floats about 6 feet upstream from the face of the dam. but control woody vegetation. The layer of stones should be at least 12 inches thick and must be placed on a bed of gravel or crushed stone at least 10 inches thick. Tie the logs end to end as close together as practicable.
Livestock
Complete fencing of areas on which embankment ponds are built is recommended if livestock are grazed or fed in adjacent fields. Fencing also enables you to establish an environment beneficial to wildlife. Hand placing gives more effective protection and requires less stone. This bed keeps the waves from washing out the underlying embankment material that supports the riprap. They generally are satisfactory for small structures. but they are inexpensive if timber is readily available. use stones whose color is similar to that in the immediate area. If the dam is built on a curve.
67
. Leave enough slack in the line to allow the boom to adjust to fluctuating water levels. A boom consists of a single or double line of logs chained or cabled together and anchored to each end of the dam. the advantages derived from fencing are more than offset by the increased cost and maintenance and the fact that fewer animals can water at one time. and in other areas. Dumping requires more stone. Construction
Booms—Log booms also break up wave action. is usually advantageous even if complete fencing is impractical. On some western and midwestern ranges.Agriculture Handbook 590
Ponds—Planning. install a gravity-fed watering trough just downstream from the dam and outside the fenced area. you may need anchor posts on the face of the dam as well as at the ends to keep the boom from riding on the slope. provide a berm on the upstream face to support the layer of riprap and to keep it from sliding downslope. If possible. Allow grass and herbs to grow through the riprap to blend with surrounding vegetation. the auxiliary spillway. If you use double rows of logs. Riprap should extend from the top of the dam down the upstream face to a level at least 3 feet below the lowest anticipated water level. If you fence the entire area around the pond and use the pond for watering livestock. particularly the earthfill and the auxiliary spillway.

it may lead to failure of the dam. A heavy layer of sand or gravel on the fill discourages burrowing to some extent. do not keep any aquatic growth or shoreline vegetation and take special precautions in planning. and water supply.Agriculture Handbook 590
Ponds—Planning. and operating and maintaining the pond. Fill any rills on the side slopes of the dam and any washes in the auxiliary spillway immediately with suitable material and compact it thoroughly. In malaria areas. beaver. Repairing damage immediately generally eliminates the need for more costly repairs later. particularly hogs. Gambusia minnows are particularly effective in controlling mosquitoes. but in time it rusts out and needs to be replaced. If seepage through or under the dam is evident. Inspect your pond periodically. encourage bacterial development. Lack of operation and maintenance has caused severe damage to many dams and spillways. but if neglected it may increase until repair becomes impractical and the entire structure must be replaced. Keep the water in your pond as clean and unpolluted as possible.
68
. outlet structures. In some localities burrowing animals such as badgers. Design. mow it frequently and fertilize when needed. Most states in malaria areas have health regulations covering these precautions. Damage may be small. Fertilize as needed and reseed or resod these areas. algae and other forms of plant life may become objectionable. Using a submerged inlet or locating the inlet in deeper water discourages beavers from the pipe inlets. For these reasons you must be fully aware of the need for adequate operation and maintenance. and watering troughs free of trash at all times. and you should carry out all measures required. no matter how well planned and built. Construction
Operating and maintaining the pond
A pond. If this damage is not repaired. If the plant cover is protected by fencing. In areas where surface water encourages mosquito breeding. keep the fences in good repair. install protective devices. pave the approaches to the pond with small rocks or gravel. If fencing is not practical. Poultry netting can be used. consult an engineer at once so that you can take proper corrective measures before serious damage occurs. and prairie dogs cause severe damage to dams or spillways. gophers. or any other source of contamination away from the pond. To maintain the protective plant cover on the dam and on the auxiliary spillway. must be adequately maintained if its intended purposes are to be realized throughout its expected life. Some structures have failed completely. stock the pond with topfeeding fish. bedding grounds. feeding yards. If the upstream face of the earthfill shows signs of serious washing or sloughing because of wave action. They can cause disagreeable tastes or odors. and produce an unsightly appearance. In some areas. building. recreation. These regulations should be followed. Divert drainage from barn lots. Do not permit unnecessary trampling by livestock. Mowing prevents the growth of woody plants where undesirable and helps develop a cover and root system more resistant to runoff.
Keep pipes. such as booms or riprap. valves. trash racks. Be sure to examine it after heavy rains to determine whether it is functioning properly or needs minor repairs. Clean water is especially important in ponds used for wildlife.

or any of the other purposes discussed in this handbook. but only if it is safe. your family and friends may picnic beside the pond or use it for fishing. if the water is to be used for swimming. Design. attract people so that there is always a chance of injury or drowning. For example. and brush and all rubbish. wire. and fences that might be hazardous to boating and swimming. You should become familiar with those that apply in your state and be sure that you and your engineer comply with them. like any body of water. In many states small farm ponds are exempt from any such laws.
During construction
Your contractor should take other safety measures during pond construction. stumps. irrigation. the latter require a minimum depth of about 10 feet of water. Construction
Pond safety
Ponds. and you can never tell what a small child passing by may do. swimming. This is particularly important if you intend to open your pond to the public and charge a fee for its use. Remove all undesirable trees. planks. construction. at swimming areas to facilitate rescue operations should the need arise. whether you authorize such use or not. or ice skating. Place lifesaving devices. You can take some of the following steps to prevent injuries or drownings and to protect yourself financially. You may find that you need to protect yourself with insurance. ropes. and operation and maintenance of ponds. However. Find out what your community or state laws are regarding your liability in case of injury or death resulting from use of your pond.Agriculture Handbook 590
Ponds—Planning. You may be planning to build a pond for watering livestock. Your pond can become a source of pleasure as well as profit.
69
.
Before construction
Almost all states have laws on impounding water and on the design. You may wish to provide for beaches and diving facilities. guards over conduits are required. junk machinery. boating.
After completion
Mark safe swimming areas and place warning signs at all danger points. Place long planks or ladders at ice skating areas for the same reason. such as ring buoys.
You should decide how the water is going to be used so that you can plan the needed safety measures before construction starts. or long poles. Eliminate sudden dropoffs and deep holes.

Its purpose is to intercept the flow of seepage along the pipe or conduit and to make the seepage path longer. Interrelated elements or components of a designed system. A flat. Point of known elevation for a survey. usually at right angles to an axis. or around a dam. The rate of flow of a fluid through a unit cross section of a porous mass under a unit hydraulic gradient. level cross section element normally in an open channel. whether open or closed. The process by which the soil grains are rearranged to decrease void space and bring them into closer contact with one another. or both. A part of an open channel spillway where accelerated flow passes through critical depth. just upstream from the dam. A section formed by a plane cutting an area. to protect the side slope from erosion. over. Any channel intended for the conveyance of water. usually level. thereby increasing the weight of solid material per cubic foot. The spillway designed to convey excess water through. in a dam cross section. or trench. spillway. A constructed barrier installed perpendicular to a pipe or conduit and usually made of the same material as the pipe or conduit. Construction
A portion of a valley cross section higher in elevation than the valley floor. It may be located in either the upstream side slope. An area from which earthfill materials can be taken to construct the dam.Agriculture Handbook 590
Glossary
abutment
Ponds—Planning. downstream side slope.
cross section
71
.
antiseep collar
appurtenance auxiliary spillway
backslope bench mark
berm
boom
borrow area bottom width
coefficient of permeability compaction
conduit (pipe) control section
core trench (excavation) of a trench) critical depth
Depth of flow in a channel at which specific energy is a minimum for a given discharge. A strip of earth. The slope above the valley floor. May be in relation to National Geodetic Vertical Datum (NGVD) or assumed for a given project. Design. A floating barrier extending across a reservoir area. The trench in the foundation material under an earth embankment or dam in which special material is placed to reduce seepage. The downstream slope of an embankment. or structure.

A soil piping and water seepage control device installed perpendicular to a pipe or conduit. which permanently impounds and stores water.
filter and drainage diaphragm
flow depth foundation freeboard
72
. sand. Its purpose is to intercept the water flow along pipes or conduits and prevent the movement of soil particles that makeup the embankment. aggregate. The portion downstream from the control section that conducts the flow to a point where it may be released without jeopardizing the dam. If there is no auxiliary spillway.Agriculture Handbook 590
Ponds—Planning. traps sediment.
design elevation
diaphragm drain
drawings drop inlet earthfill
effective fill height
embankment excavated pond
exit channel (of an open channel spillway) fill height
The difference in elevation between the existing ground line and the proposed top of dam elevation. including allowance for settlement. and/or controls flood water. across a watercourse or natural drainage area. gravel. See Antiseep collar. consisting of a single. A vertical entrance joined to a barrel section of a principal spillway system. Design. Soil. The difference in elevation between the minimum settled elevation of the top of dam and the highest elevation of expected depth of flow through the auxiliary spillway. An appurtenance installed in the dam and/or its foundation to safely collect and discharge seepage water. A graphical representation of the planned details of the work of improvements. or rock construction materials used to build a dam and its components. The surface upon which a dam is constructed. A structure of earth. Construction
dam (earth dam)
A constructed barrier. or similar material raised to form a dam. A reservoir constructed mainly by excavation in flat terrain. The height above a defined datum describing the required elevation of pool that will provide the required temporary storage. The depth of water in the auxiliary spillway or any other channel. gravel. or multizones of. together with any associated spillways and appurtenant works. The difference in elevation in feet between the lowest auxiliary spillway crest and the lowest point in the original cross section on the centerline of the dam. the top of the dam becomes the upper limit. A relatively short embankment section on the downstream watercourse side may be necessary for desired storage amount.

such as grain straw or paper. both mineral and organic. Design. or ice and has come to rest on the Earth’s surface either above or below the principal spillway crest. 2:1 (meaning two units horizontal to one unit vertical). gravity. The vertical portion of a drop inlet.
73
outlet channel outlet section peak discharge
pond
pool area principal spillway
profile
propped outlet riprap
riser sealing
sediment
settlement side slope (ratio)
site investigation
. or has been moved from its site of origin by water. A representation of an object or structure seen from the side along its length.g. The lowest ungated spillway designed to convey water from the reservoir at predetermined release rates. The maximum flow rate at which runoff from a drainage area discharges past a specific point. Solid material. The location for storing water upstream from the dam. e. usually expressed in “n”:1. A structural support to protect the outlet section of a pipe principal spillway. air.. A loose assemblage of broken stones commonly placed on the earth surface to protect it from the erosive forces of moving water or wave action. A section of open channel downstream from all works of improvement. The downstream portion of an open channel or of a principal spillway. A still body of water of limited size either naturally or artificially confined and usually smaller than a lake. Construction
hooded or canopy inlet inlet section (of an open channel spillway) mulch
A fabricated assembly attached to the principal spillway pipe to improve the hydraulic efficiency of the overall pipe system. The process used to close openings in soil materials and prevent seepage of water.
A natural or artificial layer of plant residue or other material. The portion upstream from the control section. on the soil surface. Movement of an embankment or structure during the application of loads. Site visit to evaluate physical features of a proposed project or watershed including soils data and characteristics of the watershed. that is being transported in suspension.Agriculture Handbook 590
Ponds—Planning. either on an open channel bank or on the face of an embankment. The ratio of horizontal to vertical distance measured along the slope.

to regulate the discharge of water. The theorical flow rate through the full flow cross sectional area of a porous media. and workmanship for works of improvement.
specific discharge
spillway
stage
storage volume
temporary storage top width
valley floor vegetative retardance visual focus
74
. Construction
specifications
Detailed statements prescribing standards. The elevation of a water surface above its minimum plane or datum of reference. either manually or automatically controlled. An element in the landscape upon which the eyes automatically focus because of the element’s size. materials.Agriculture Handbook 590
Ponds—Planning. or texture contrast with its surroundings. dimensions. color. It may contain gates. form. The horizontal dimension (planned or existing) across the top of dam. density. The total volume available from the bottom of the reservoir to the top of dam. Design. Part of a valley cross section that is level or gently sloping. The volume from the crest of the principal spillway to the top of dam. The amount of hindrance to flow caused by the type. and height of vegetation. perpendicular to the centerline. An open or closed channel. conduit or drop structure used to convey water from a reservoir.

The following formulas give the area of some common shapes.14 r 2
V = volume of excavation (yd3) A = area of excavation at ground level (ft2) B = area of excavation at the middle depth of the pond (ft2) C = area of excavation at the bottom of the pond (ft2) D = average depth of the pond in (ft) 27 = factor converting cubic feet to cubic yards Note: When using meters for area and depth. The formula would then be:
6 where: V = volume of excavation (m3)
Quadrant:
Quadrant A =
r
π r r 2 or 0. Construction Estimating the Volume of an Excavated Pond
The volume of a pond can be estimated by using the prismoidal formula:
Rectangle:
l w
( A + 4 B + C) × D V=
6
A B
27
Rectangle A = wl
Circle:
A B C C D
r
Circle A = πr 2 or 3.67 sh
s
This formula can be used for ponds of any shape. Design.Agriculture Handbook Appendix590A
Ponds — Planning.7854 wl 4
75
. The area of excavation can be determined either by planimetering the shape on the plans or by using geometric formulas for areas. 27 is not needed.7854 r 2 4
(
)
( A + 4 B + C) × D V=
Parabola:
h
Parabola A = 0.
Ellipse:
w
Ellipse A =
l
π wl or 0.

The area of the surface, the middle depth, and bottom can also be determined by using a planimeter. In this example, the pond was drawn at a 1 inch = 40 feet scale and has a depth of 8 feet. Step 1: Measure the surface area (A) using a planimeter. Convert the measurement from square inches into square feet. (A factor of 1,600 is used to convert square inches into square feet for a scale of 1 inch = 40 feet.)
A = 10.0 in 2 × 1, 600 = 16 , 000 ft 2

Step 4: Use the prismoidal formula to estimate volume of excavation in cubic yards.

V = V =

(A + 4 B + C) ×

[

8 6 27 16, 000 + 4 × 12, 320 + 8, 800

(

)

6

]× 8

27

74, 080 8 × V = 6 27 V = 3, 658 yd 3

77

Agriculture Handbook 590

Ponds — Planning, Design, Construction

78

Agriculture Handbook 590

Ponds — Planning, Design, Construction

Appendix B

Flood-Tolerant Native Trees and Shrubs
The plant lists in tables B–1 through B–4 were taken from the Corps of Engineers Technical Report E-79-2, Flood Tolerance of Plants: A State-of-the-Art Review. The ratings used are intended only to be a relative classification. Tolerance will vary with local conditions. The plants are divided into four groups: very tolerant, tolerant, somewhat tolerant, and intolerant. Each plant was also given a range coinciding with the plant growth regions, figure B–1, developed from USDA Miscellaneous Publication 303, Native Woody Plants of the United States, by William R. Van Dersal.

Flooding creates several conditions that are unfavorable to most woody species. The most critical condition appears to be the depletion of soil oxygen that is critical to plants. The lack of oxygen favors anaerobic bacteria, which can lead to the development of toxic organic and inorganic byproducts. A plant’s ability to survive flooding is dependent on many factors; among them are flood depth, flood duration, flood timing, plant age and size, wave action, and substrata composition.